now you're moving the goalpost. the vast majority of folks that don't return them leave them out of the way

I question this assertion. What 'out of the way' exists in the parking lots you frequent? Every one that I can think of offhand consists of parking spaces, areas for people to walk from their cars, driving lanes and little else. Anywhere you could leave it other than the designated place is causing a problem for someone.

Tell that to the dent in my door.