Yes, I took the two carts that people had left abandoned in the parking lot, back to the corral by the entrance and locked them back in with the others. It was not "here take my cart" like the scenario you mentioned.
EDIT: First one was on my way into the store, someone had left it so I used it and returned it. Second was just when I was about to leave in my car, watching a young couple, maybe early 20's unloading into their car. Guy gets in and starts the car, girl takes the cart and just props it up on the curb, they were near the back of the parking lot, gets in the car and they leave. So, I grabbed it and returned it to the store corral.