I think that this is also a deterrent for people that would use a cart for a few items that would actually fit well enough in a basket. Just imagine if everyone was walking around, pushing a cart. Again, like others have said, I don't think it will stop all of them, but it will make it more impractical for some.
A friend of mine would always go up to the mall on the weekends and spend a few hours combing the lots looking for carts that needed returned. Most people it seems would rather just leave the cart in the lot than get their quarter back. We would always make enough money to go to the buffet and a movie. Lazy people made me money!
