The other issue not mentioned is the last minute cancels (Within 4 days of the arrival date,) and those campgrounds on a national reservation system.
These cancels take four days to appear, so the general public does not know that the space is available. It appears reserved, meanwhile the site is empty.
If a reservation is made, the full amount should be deducted and if you cancel, you lose the entire amount. This would slow down those making reservations at four campgrounds and then canceling three at the last minute.