Is it really on the device manufacturer that people don't change the default password? That's advice that's been around so long and it's the first thing they tell you in computer training.
Default passwords have their use cases for testing, ease of set-up, and for device recovery.
Yes, it should be. Sending someone a device with usr/pwd as admin/admin, for example, is completely reckless if it doesn't prompt the user to change it during setup.
it's the first thing they tell you in computer training.
You shouldn't need specialist training to use basic home products, and you shouldn't have to put up with extremely compromised security in the event of you not being technically-minded or you blitz through installations pressing next next next. Not everyone is or can be technically minded.
Plenty of products have protections in place designed to protect users in the realistic event that not everything will be used flawlessly 100% of the time.
PCs aren't shipped to you with always-on root-level access, gas hobs often have features to turn themselves off if they detect they've not been ignited, cars have all kinds of safety features, pills come in pop-packs to discourage taking a load at once by swigging a bottle, Switch cartridges taste like shit to stop babies from choking on them, etc. sure, not all of these should be legally required, but some absolutely should be.