Caravan site price structure

If you stay in a hotel, you either pay per person or per room per night.

But when you stay on a camp site, not just CC sites, the price structure has a lot of options.  Things you could be paying for are, pitch, adults, children, pets, awning.  Sometimes the list of extra's seem endless.

Why is it common practice to have so many options when booking a camp site.  I feel like I should be receiving a maths degree everytime I check in.