Why don't carts have a little handheld scanner, then you pay at a scale?

I’ve been doing this for years! My local grocery has a little scanner you can take around with you, I carry 2 wicker baskets, scan items as I fill them, and then the self checkout lane reads a code from the scanner, I tap to pay, and walk home. It’s honestly seamless.

I'm going to assume you're in a country where they have the self checkout things which have a 'bagging area' of some sort wit a scale under it?
In the Netherlands we have selfcheckout without this weighing. You walk into the store, grab a handscanner, and as you walk through the store you can pick something up, scan it, put it in your own bag and continue. When you get yo the register, you scan some barcode on the screen of the register woth your scanner, touch your nfc bank card to the terminal, and walk out. No need to take anything out of your bag.
Sometimes they do random checks, then some employee comes over and scans a few items from your bag. But you can just let it be their problem. They'll usually put the stuff they've taken out back in again aswell.
- We have something similar in the UK.
  
  Typically, you need to already be a member of the stores loyalty/rewards scheme, so that they know who you are before you start scanning items. And if anything goes wrong, like you try to rip them off, or a technical issue with the scanner, you get locked out from using the scanners until you call their support line and sort it out.
- We had those briefly where I was in the states right before and during COVID. It was so nice being able to pack things in bags neatly and just ring it all up at the end easily.
- Some places in the US have this! My local Stop and Shop does.

At least in Germany, at a lot of Rewes (supermarket chain), this is absolutely a thing and very common. You can place the handheld barcode scanners in a specialised holder on the cart handle and then scan as you go, and neatly package all your stuff before going to the checkout and paying at a terminal. If even Germany has got this by now, then every other country on the planet surely does too lol.
- Our Edeka has a system like that too.
  
  So does Kaufland and Albert in the Czech Republic
- Do they make it easy to put something back if you change your mind?
  
  Yup, you can just edit the amount of items you scanned. Also makes it easier to "scan" an item in bulk.
  They dont check the cart weight, instead they just randomly pick out people where they go through their scanned items and check that nothing else is in the cart. I'm being checked about once every 20 times I go.

Some giants have had handheld scanners for a decade... You just grab one as you walk in, scan and pack everything and hand it to the cashier on way out.
- And you need a membership card because of course you do
  Also why involve a cashier when self-checkout is available?

I heard some grocery chain was experimenting with rfid chips on all their products so you can just load up and leave and sensors at the door detect what you're carrying and charge you the appropriate amount automatically. Personally I'd rather pull up to a register and have it show me a list of what's in my cart and the total price rather than automatically charging, but otherwise it's not a bad idea.
- I'm with you. Automatically charging sounds like a nightmare. I still always want a human to verify everything a computer says. I don't trust a corporate entity to not try and rio me off.
  
  Well you'd get a ticket or a screen showing it all before paying? Like when you scan yourself.
  My concern is the e-waste of a trillion RFID chips.

That exists and it's really nifty. At least in France, you have them in most big brand supermarkets. The downside is that it requires a user account.
- Very interesting! I haven't had the chance to do groceries in France yet. I'd love to see it though. It just seems so nice.
- The downside is that it requires a user account.
  Most large US supermarkets make you have loyalty accounts to get their real prices anyway as it is, in exchange for your buying habits, otherwise everything is marked up.
  
  I really hate this shit and honestly I feel like it should be illegal. Like, offer discounts for the loyalty program members, sure, whatever, but the price on the shelf when you pick up the item should not be able to have contingencies attached.

The grocery store I often go to had these barcode scanners you could borrow at the entrance and scan your stuff as you go, along with scales on which you could print a barcode sticker for the stuff you pay by weight.
Once you were done, you'd scan a QR card at the self-service checkout to upload all the stuff you scanned, then pay.
It was awesome, you could just pack as you go. Unfortunately they scrapped the project once they found out that the amount of theft was significantly higher with this system. So yeah, we can't have nice things 😒

Walmart doesn't even let you do the scan and pay thing with your phone unless you're a Plus member. Which is fucking stupid. We basically already have a scanner with the ability to pay in our pocket, and they even have systems that let you do exactly what you're asking about. But then they make you pay extra for it. Like, you're already trying not pay employees and you expect me to pay you to do what a cashier does? Fuck that and fuck you, Walmart.

Theft, pretty much. They wanna see you empty that shopping cart before you leave.
You know what would be nice? Check out the Uniqlo checkout booths in Japan Video and imagine that tech connected to a single shopping cart that just charges your card when you walk through the door
- Well it's a good thing they hardly ever employ cashiers and make me go through self-checkout. I'd never steal from self-checkout.
  I'm guessing those checkouts you linked use some sort of RFID chip in the tag? Pretty interesting!

Grabbing a scanner at the door makes more sense otherwise they would have to be made waterproof since people take and leave their carts outside.
I worked for a company that did a demo using RFID tags. Every item had one and you just walk through a scanner when you're done shopping and it rings everything up instantly.

Walmart spent millions on rfid trying to do this. Howevera cart full of razor blades would always not read something so they gave up.
as others have said what you ask for evists - but only where most people are honest enough to not cheat. Where stores don't trust everyone the cost of verification is more than any savings.
- Sam's Club, owned by Walmart, does this basically.
  You scan items with your phone, check out, then walk under this arch camera things to leave, I haven't been stopped to be manually checked in ages.
  
  Sams club attracts different customers from WalMart and so they don't have the same crime concerns.

Tesco in the uk does this.
Coincidentally enough this post a few down from yours (on my feed) shows a trial for the second part of your post
- I think other large supermarkets do too.

We have this at my local grocery store (Meijer) down in the states. You use the grocery store’s app and scan as you go then pay at a kiosk. There’s a scale at the kiosk to weigh produce or I think there’s an app for that too. No need to weigh the whole thing. It’s called “Shop & Scan”.

Yeah, seen something like this in the UK. You take a scanner and scan everything as you shop, then just lay the bill as you exit. To begin with they even offered a discount I think. But they didn't have a weigh option, just that they'd check some carts 'at random'. My understanding was, like self checkouts, even if there's a little more theft it's more than made up for by less workers.

If you pack your groceries in boxes in the cart, wouldn't that throw off the weight at the checkout?
Sam's Club does it all with a self-checkout app and cart-scanning cameras at the exit. If you only get one or two things and don't use a cart, then an associate needs to spot-scan on the way out, but otherwise it works great!

S Chain in Finland offers this, you have to of course have their customer loyalty card.
- But if you want to just use the self-service cashier automats, I think the loyalty card is optional. For scanners though it might be required, I've never used those. The self-service cashier points are easy enough for me. 😊
  
  For the scanner you need the card, yes. For the self check out only no

Honor system wouldn't work in all places unfortunately

I do this with my phone at meijer. No need for a device when you're phone can scan already.

amazon fresh stores do something like this.

They had this at Stop & Shop for a while in the US. Don't know if that's still how it works though.

Already exists and being used, search for "smart shopping carts"

Sam's Club in America you can use their app to scan your stuff and pay. They check your receipt on the way out.
- My Sam's Club has two big arch camera things that scan your items as you walk past. Person at door that normally scans ~3 items and receipt, just waves and says "You're good to go!". Been like this for months.
  Scan and go is amazing.
  The arch is kind of cool but they just had to scan ~3 things manually before so it's not that game changing. But nice.

There’s at least one UK supermarket that lets you do this.
Info:

In Switzerland big super markets have this with handscanners. You can also use the Supermarkt App and scan the stuff with your smartphone. When you leave you just checkout and payment is processed automatically if you have set it up or you can pay at a terminal. Sometimes they do random checks.
- Same in Belgium, no scale involved, just a handled scanner you bring in the shop. At checkout you give (or put back depending on the supermarket) the scanner, then an algorithm tell you if you're elected to a partial control (in which case a cashier scan some of the articles, again there are some rules depending on the brand of supermarket - some ask rescan 5 random products, some 10, some explicitly list most valuable items, some require the cashier to count items,...). I say an algorithm because experience show it's not just random (for example in the supermarket brand I most often go, if you cancel an item on the scanner, you're 100% sure to have a control).

We have that in one shop. It started with just a scanner and at the register you'd get random searches. By now the scale is integrated into the cart.
It sucks a bit because with the first system you could quickly scan ten items and throw them into the cart. But now you have to wait a bit after throwing something into the cart for the scale to give the ok.
They don't weigh at the end because that way you can have your shopping bags or boxes in the cart. That way the cart's weight at the beginning is registered as 0 and when you're done shopping you just have to lift your bags directly from the cart into your car. I guess that could be mitigated by having a scale at the entrance of the shop.
But for all the waiting after scanning one item it's still much nicer than having to load everything from the cart to the register and then back into the cart again.

We'll, there's Amazon go, which is actually slightly better than having to scan and check out: https://en.m.wikipedia.org/wiki/Amazon_Go#%3A%7E%3Atext=Amazon+Go+is+a+chain+of+convenience%2CKingdom%2C+operated+by+the+online+retailer+Amazon.
Also Kroger did what you are recommending like 10 years ago, but it looked silly compared to Amazon go, so it didn't really stick in my area.

We do in Switzerland.
Not attached to the cart, but you can pick up a scanner at the entrance, scan all your stuff and at the checkout you scan your scanner. No need for the scale at the end, though.

Ikea does this with their app, but generally, you go to ikea to get one or two items, so it doesn't really speed up the proccess of checking out

These exist, albeit not attached to the trolley (which makes sense).

Stop & Shop in the US does this (or at least it did? I never used it so I barely pay attention to it lol). There's like a wall of handheld scanners you can pick up when you enter and a little place on the cart for them to go in. You can scan and bag your stuff as you go and then pay at a special register.
- They definitely still do it at both locations in my town. I shop for one, so I've never felt the need to try it out, but I see other people using them regularly.

There is a trial going on in Gateshead (UK).
https://www.bbc.com/news/articles/c0rzvrjkklko

Tesco in the UK has had handheld scanners for years, and are trialling scales.
- Tesco, Sainsbury's, Waitrose all do this in the UK

We have that in France too.

https://youtu.be/izjhx17NuSE
If you jump to the 16 minute mark of this video, you can see engineers in the 90s brainstorming the concept of having a scanner built into the cart. The idea has been around for a while.
The whole video is a time capsule in itself.