When I was a kid, we would go shopping with my mom, and one of us would take the cart back to the store. We were taught that it was unacceptable to just leave it in the parking lot, and never felt put out to have to take it back. So, then someone got the bright idea to put areas in the parking lots so people wouldn't have to go all the way back to the store. What amazes me are all the justifications for not putting them where they're supposed to go.
However, a few years ago I was watching a Judge Judy, and a woman was being sued because she just left her cart and it rolled and damaged another car. Her defense was that everyone else was doing it, and it was "an act of God". Judge Judy was having none of that, the ruling was that if there was a place provided to put the cart, then it was her responsibility to put that cart in it so that it was secure and would not damage anyone's car.
So, just for kicks I started looking it up to see if you are indeed responsible. Turns out, you could be. The store is only liable if they are negligent and do not provide an area for the carts. If you ignore that and just leave it out in the open, it rolls into a car and damages it, and someone witnesses it, you could be on the hook for it. I think of that every time I'm putting my cart back where it can't do any damage.
It is more than just being inconsiderate.