We had a similar problem with the US Forest Service in Arizona last winter.
Upon entering the Chola campground at Lake Theodore Roosevelt we stopped here to pay our expected fee.
Hard to see but the old "Iron Ranger' payment slot is painted over but still there.
This sign told us just where we could purchase a "Tonto Pass" so we could camp here.
It required a 14 mile drive to purchase a pass. The pass cost me $3 as I am a Golden Age Pass holder.
So about a gallon of diesel fuel for a $3 purchase.
When asked the next day why we just couldn't pay the "Iron Ranger" the district ranger told me: Emptying the "Iron Ranger" and counting the money was an unpleasant task for his people.
I'm afraid some Government employees think we are there to serve them.