I always make a point of parking where no one is parked and when I return there is usually someone parked right next to me in the middle of nowhere. Sometimes, I think the behavior is intentional and the door strikes are intentional. A year ago I bought a new Silverado Crew Cab, parked at a ski area and ended up with scratches on the passenger rear door. It was pretty obvious to me that the person not only hit the door but left it against my vehicle for a while as there were also up and down scratches from asshats climbing in and out of the vehicle as it moved up and down. I've tried everything to get the scratches out and nothing seems to work. I'd like to choke the bastards.
It's a combination of laziness and a total lack of respect for other peoples property. It would be so easy to be careful but they don't even try.