I guess I'm a little surprised that some of us don't put the carts back. It's always seemed to me to be rude to leave a cart out loose, expecting someone else to take care of it. Especially when the only vacant parking space holds an errant cart, or when a cart takes off down the lot and runs into someone's parked car. It's just like if I knocked some cans off the shelf in the grocery store, I don't expect someone else to pick them up for me. I made the mess, I clean it up. I used the cart, I put it back.