Some of our thrift stores have carts with a fishing pole like thingey on top so they won't go out the door. But with grocery stores, I can see this because no way am I going to tote a heavy load out the door way down the parking lot to my car. I do with the grocery stores would get with this.
Some of our grocery stores were talking about putting some sort of lock on the wheels and some sort of controls around the edges of their lot so the cart wheels would not roll after they passed that edge. All talk so far.