The following came from the park's homepage: "Visitors have the option to select from tent sites and standard or pull-through RV sites featuring water, sewer, and 30 or 50 amp power connections".
Seems to me visitors can get 50 amp sites with no mention of being a member of anything.
The website says this about camping club members:
For Camping Club Members
Yonah Mountain Campground welcomes campers in Coast-to-Coast, AOR, Good Sam's, and RPI camping clubs. If we are not your home campground, remember that reservations must be made through your camping club to qualify for discounted rates. Otherwise your stay will be billed at the rates listed above. Good Sam's members can book reservations directly with us and receive 10% off when you show your membership card at check-in."
I see nothing on their webpage saying anything about non-members. A 50 amp site is $42 for anybody and you can get a 10% discount for Good Sam or military service. Seems reasonable to me. I don't see what there is to complain about.