Area, of the Country determines much plus features of campground, or is it a Resort with very much upgraded everything including clientele.
In Michigan we pay about 35.00 plus two dollars if we use air conditioning plus tax. In general 35.00 to 37.00. Southwest is about the same.
"Destination parks" are about 55.00 or more plus tax like the two, in Nashville.
State parks in Tn and La were about 25.00 pus or minus but better quality than many many. Canada was about 40.00 to 55.00 depending. Private campgrounds were cheaper, at the time. It's been about 5 years since we camped up there.
We've stayed at some excellent RV Resorts for about 55.00 to 60.00 in Michigan etc and about the same in the Southwest but not quite up to that standard.