I think there is both right and wrong on the side of the OP.
Westernrvparkowner is correct about the fees involved and you have to cover them.
Having owned a Hotel I can tell you Reservations are the bain of your existence and they are a costly system in terms of manpower to keep up to date and running smoothly and accurately.
But I also think that many parks are trying to gouge us with unreasonable reservation refund costs and time limits and I would encourage everyone to push back on those and tell the parks why you are not using them.
When I see a reservation cancellation that I dont think is fair and I really want to stay at that place I email and sometimes call them and ask them to change it to XYZ that is more favorable to me...most do this and accept less deposit under better terms.
One thing I would point out to the OP is that reservations made far in advance are I think more suspect by the management to be cancelled than ones made a bit closer to the actual date. Try revising your reservation habits and I think you will not have these issues.