Even a few state parks do it now. It takes a legislative act to increase fees, so some states have added a "dock fee" or a "day-use" fee to every campsite. SO advertised site say, $20 a night, becomes $26 a night. We would probably stay anyway, but would like a bit of honesty.
We all (campers, RV'ers) understand costs go up sometimes - and the state parks are often jewels and less priority than other budget items - but honesty about the fees should trump an arrival add-on. Just seems sneaky to me, same with the hotels and cell phone service companies. Deception seems to be the rule of the day in a lot of business dealings and advertising.
Price plus tax, should never be price plus tax plus fees. And just because it calls itself a resort does not mean it is one.