The two of my (American) kids who've gotten old enough to buy stuff on their own, even if it's just us sending them into a convenience store with money for some

The two of my (American) kids who've gotten old enough to buy stuff on their own, even if it's just us sending them into a convenience store with money for something, have immediately recognized this system as idiotic, and they frequently complain about it. It's so plainly-stupid that, literally, even a child can see it.