I think a lot of the problems come from the disconnect between expectations and realities of RV parks in the Yellowstone/Grand Teton area. The expectations are with millions of wide open acres the parks should reflect that abundance of acreage. The fact is there is very little in the way of private land available and what is available is priced astronomically. On top of that, many conveniences people have come to expect are only marginally available in the area. Things like Cellular service and wifi providers are very limited and not comparable to the service you get around cities.
Combine the high land costs with a short season and you get high site rental rates. A site that might be $30 most places run in the $50s around the parks. I would imagine the surly attitudes people feel they encounter is partially a response to the park's management hearing repeatedly that people have stayed in better parks for less money elsewhere. A factual response to those complaints may truly be: "Rates are what they are, the wifi is as good as it can be, and we really can't improve your cellular service." To many people those park employees responding truthfully is interpreted as those employees being rude and uncaring. Sometimes the truth really does hurt. The fact is there really isn't a park anywhere near Yellowstone or Grand Teton that would qualify as a great stand alone destination. Even the best parks are nothing more than good places to park your rig while visiting the national parks. The best approach is to realize you are going to Yellowstone and Grand Teton to enjoy the national parks, not the RV parks.