When I was younger & angrier, I thought of making a remote-controlled shopping cart and whenever someone didn't put their cart away, I would pilot the remote-controlled cart behind their vehicle just as they were pulling out.
Going out and collecting loose carts was my favorite part of retail. Got to be outside, walk around, no dealing with customers, and no supervision so be as slow and lazy as you want.
Please, leave all the loose carts you want. If everyone returned them, I'd have to be inside dealing with a Karen or screaming psycho or incontinent old person bursting their colostomy bag in the middle of the candy aisle and trailing it through the store behind their scooter (true story).