I know that this is the cycling community, but... Why would someone choose to bike to Costco unless they are an employee? Are there people who do not purchase a carload of goods when they go? Cyclists are nowhere near Costco's target demographic, so this really doesn't seem surprising.
Are there people who do not purchase a carload of goods when they go?
For starters, Costco has a pharmacy, optical and hearing aid departments, as well as a bakery, among other services. None of these require a large SUV or even a small car for.
Second, you don't have to buy a carload of stuff from costo, and even a basic cargo bike or bike trailer or panniers can get you a ton of products. Most shoppers won't be filling more than one cart.
The point is, they have a bike rack, which currently serves no purpose the way it's been installed. This low effort doesn't benefit them or their non-car customers.
I have friends who costco is their nearest grocery store. they live just outside of walking range. For them it makes sense to bike there and grab just one thing.
Honestly, if you just need to pick up prescriptions or OTC stuff. Condoms at Costco are cheap, and some of my medicines are like...$47 at Costco or $130+ at CVS. The whole medicine section is great.
My two bike bags can also fit 40L each IIRC. Lots of room for groceries, though I tend to pick up at closer places and save Costco for when I really whittle down my freezer, fridge and bathroom supplies.