Why do parks ask for license plate information?

I would have to assume that in the event that a problem comes up later they have a way of tracing that license plate for LEO's. I know many years ago my parents owned a motel and resturant and the LEO's that always stopped in for coffee always told them to get license plates in case of future problems. I know most campers aren't going to cause a problme but there has to be a bad one in every bunch. It certanily isn't a problem for me to be asked for my license plate number.