Weis Markets here in PA was testing it in a few stores last year. The jury is still out if they will implement it in all their stores. BJ’s Warehouse club stores (similar to COSTCO) used to have this; in fact, it was the first store where I ever saw this and that was in the late 80’s. Lidl had this until recently.
Honestly.....I like it. Its a good idea. People tend to bring the carts back when they have some skin in the game. When they know their laziness will cost them something.
The problem in the US is our largest denomination common coin is a quarter. That might not offer enough incentive. Over in Europe they make it a whole Euro which hurts a bit more to lose just because you’re lazy and don’t want to return your cart.