Also in the rare case that a cart is abandoned someone will quickly bring it back or use it themselves. The person abandoning the cart basically pays the finder
At my Aldis some of the more industrious folks will happily return your cart for you to get the quarter.
I remember people used to do this in Germany when I was a kid ~20 years ago at bigger shops. They would walk up to people loading their cars and ask if they can return the cart for them. I always perceived it as a form of begging. Nowadays I don't see it anymore.