Well, from an adult perspective I can see where you're coming from re the MacDungheap cash register.
However... young kids love playing "shop"; it's a good way to practice handling money, giving change etc. My daughter used to love her Barbie "talking" cash register, although it drove us up the wall.
The target age group (3+) won't care about the future implications - at that age the burger bar is a fascinating place. And by the time they realise what working there is really all about they will have long since trashed/lost/given away the toy.