The post above yours by indyfabz shows the issue. I've worked in the tourism industry, and if you have a site that is not occupied for a night, it cannot be got back again on the books, unlike a physical item that might spend a night for 20 on the shelves and still be sold. The opportunity to sell that site for a night disappears. It's called, or used to be called, perishable inventory. It's the same as vacant beds in a motel, or an empty seat on an aircraft about to take off, or an empty tour bus. The money still has to be paid for that room or seat or bus.

If you jack the price up way high, you are either sending a message that you don't want people using those sites, you think them too much trouble, or you have an overinflated sense of your own importance.

Machka has a couple of brilliant stories about this sort of thing, and in one case I can recall, she moved on elsewhere and found digs that were cheaper and much, much better in the same town.

The attitudes in Europe are somewhat different, where there are tent sites put aside, cyclists are welcomed (at least in most cases where we have stayed), the campgrounds are well organised and laid out, and the facilities are usually clean and range from adequate to brilliant. And most importantly, the staff usually were welcoming (although the Germans along the Rhine Route were far less than that).