The biggest difference between a private park and a Govt. park be it Corps of Engineers, or just a park built by a state, is one is privately financed, the
others are Govt. subsidized. One must make a profit or close it's doors, the others can lose money forever and still remain open.
Cost of building a nice park is extremely high. A few years ago The National Assn. of Campground Owners came out with a cost figure of $14,000 per site to construct, AFTER you buy your land. That means a 100 site park costs $1.4 million dollars to build plus cost of the land, which is also expensive if located in a good location with high traffic count.
It's a matter of Govt. supplying or private industry supplying the park.