we used to experience this in 1000 trails Hershey. it was an older park with a couple sections that were small sites. Because it was a first come first serve system these sections were always the last to fill up. If you pulled in on Friday and you were almost guaranteed that would be all that was open, even if you did not fit in the site. But the tent and popup camper people paid the same dues we did, and were untitled to the same sites (even if you could fit 5 popups in the site they were using)
But than there was a new section with 50A. And you were required to have 50A camper if you parked there. How does that work?