Dont really think its any different than a motel room. The hospitality company is going to have a set check in and check out time, and you hope they give a couple hours in between to clean or check the accomidations before sending the next person over.
The problem is that there are more and more folks trying to get those sites, and more and more show up early, check out late, and computer reservations likely more often than not allow people to select an exact site that they want.
Obviously the person that checked in those folks early should have verified that the site was empty, but in areas with high density and especially on the Thurs-Mon day period the computers maximize the occupancy.
At least it didnt seem to actually cause any problems.