"It depends"
Here in Oregon we have private for profit campgrounds, state parks, county parks, NF and BLM campgrounds.
I've yet to see the latter have any RV "hookups" as all sites are primitive. I do it all the time where the parking is part of the site. There are campgrounds where the tent folk have to "hike in" from a parking area and I suppose the parking area is off limits for camping (who would want to camp in a parking lot anyway?)
The only real difference (minus hookups) is that an RV site might be longer or wider or more level than a tent site.