It's very simple....know what the reservation cancellation policy is and if you don't like it, don't book it!
On the flip side, I've had quite a few instances where campgrounds have been very accomodating when I've had to cancel or change the dates of a reservation.
Most experienced campers know that owning/running a campground is not an easy way to make a buck if you want to have a nicely maintained and updated facility. There is a need for cancellation fees.
However, charging a fee when you're calling back within 5 minutes isn't very good PR! I find that fees that are based upon when the cancellation is made are better for both parties such as the policies of many KOA campgrounds.