Reserve America does not set any of the fees you pay. They don't even get the money. It goes to the states/federal agency/campground owner directly, and they pay RA when billed monthly.
Their contracts with individual states, individual federal agencies determine how their fees are charged to the customer.
For example - the US Forest Service makes the customer pay an additional $9 per reservation on-line, where the US National Park Service does not make the customer pay any additional fee for on-line reservations. Those are both branches of the US Department of Interior.
Some states charge an on-line reservation fee even if you arrive at the CG without a reservation. Some states like Florida charge excessively high change and cancelation fees hoping to deter folks from reserving sites and reselling the reservations.
On the Reserve America page for every state/ agency is a link to a description of all extra fees charged.
Winhall Brook ExampleBe aware that many agencies have varying fees for a single campsite. Some states charge $3 or $5 more per night on weekends or holidays. Some states / federal agencies will charge $2-5 per night more for a 'water front' site than the near identical site across the road.
Some states rates go up for the 'season' and are cheaper for the 'off-season'. Louisiana charges $20 Oct-Mar and $28 Apr-Sep for the same sites at many parks.
All reservation systems have a charge for changing or canceling reservations.
Also the US Army Corps of Engineers has put new rates into the system for many campgrounds - like Winhall Brook - but the fees for individual campsites have not yet been updated. So at that CG when you go to checkout - the price jumps form $22 to $26 per night.
I talked to the office today - and they have been getting a lot of calls about the rate increase which was approved last week and just went into effect for new reservations a couple days ago.