I agree - some people just don't realize they don't have to slam. We especially find that tenters slam a lot. Everything stored in the truck or car comes out and goes back in accompanied by a slam.
At one CG we were in very close proximity to an RV with slammers - we went to the ranger station to ask when they were leaving - if they were staying more than 2 nights we were hoping to move.
A group of deaf people used to live across the road from my MIL. Every time we visited we'd hear all this slamming of doors (cars, house) from over there. They didn't hear it, but we did.