Why do campgrounds not post rates on their own websites

"Stupid is as Stupid Does" ~Forest Gump

I skip past the RV Parks that fail to show the rates on their website. By showing the rates it saves them from having to answer extra phone calls. I feel I should be able to not only see the rates but also make a reservation on the website.

Because the rates change...

They probably want to speak to any potential customers. If they are needing money, they might throw out a price then if you don't bite, then ask if you are a member of anything in order to cut the price down. Or, they are higher than other parks and want to tell you the price and why they are higher. Or...they had some high school kid do their website and didn't put prices.