If you think about it, supermarkets are one of those modern conveniences that make life a breeze. Where else will you find everything you need under one roof? All you have to do is pick things, put them in a shopping cart, and head to the cash counter where the conveyor belt will take each item to the cashier who will then scan them for you.
Imagine how annoyed this OP must have felt when the conveyor belt at Walmart didn’t work when they were shopping there and they had to move all the shopping towards the scanner by themselves. What a bummer!