I've found at least three categories:
1. Municipal campgrounds, usually around a lake, catering to camping, not RVing. RV facilities are usually limited, clientele is mostly weekend, and if the place is not well policed, young people are there to party.
2. Municipal RV parks, catering to travelers, seasonal workers, and people coming for specific events. They can vary from a parking lot with hookups to park-like settings. Most do not allow camping or camp activities (like fires). Costs are usually low, sometimes free. Many are connected to a fairgrounds, race track, rodeo, or similar venue.
3. County (and state) fairgrounds. In the agricultural middle of the country, people exhibiting at the fair often come in RVs, it is their one annual vacation. The fairgrounds will usually have extensive RV parking, often tightly spaced, with electrical hookups and access to a water supply. There may be associated, or nearby, livestock pens, or places to set up temporary pens.
When no big event is going on, at least part of this space is usually open to anyone coming by with a RV. During an event, these places will be filled and often overflowing into surrounding space with no hookups.
A number of times I've gone to a county fairgrounds and found that what is available off-season is just an adjacent commercial RV park, with more facilities and higher prices, there to cater to the fair visitors who want a bit more than what they find in the parking lots on the fairgrounds.
For all of these, what you pay and what you get varies a lot. Our city used to have an eight-site RV park near our downtown city park, and it had to be permanently closed a few years ago when it became the permanent residence of indigents and a haven for meth cooks in RVs. Other parks are still open that have degraded to this, but it happens as well in private RV parks and trailer parks.
Tom Test
Itasca Spirit 29B