gilbetron parent
I've found an anecdotal correlation that the (relatively few) people that have moralized at me about returning shopping carts also tend to dislike self-checkout at the same stores. I guess it is immoral to have someone return your cart, but moral to have someone scan your groceries? I generally don't return my cart, but I mostly self-checkout. I'm pure evil apparently.
Full-service checkout is a service that is explicitly offered by (most) stores, and yes, it's a service many people like -- in part because of the poor UX of the self-checkout machines. ("Please return item to the bagging area.")
I don't think many people would object to full-service cart return, in which employees immediately pick up your cart when a customer is finished loading their groceries into the car. But few (if any?) stores actually intend to offer that, as evidenced by the carts that sit for long periods of time strewn about the parking area.