I believe this one is pretty black and white. The park service has decided you cannot fly your toy airplanes in the National Parks. The fact that someone thinks they should, the fact they think it is a silly rule, the fact they think it shouldn't apply to them, because they are a "responsible" person doesn't really matter. They had incidences caused by people who if you asked them would say they too are responsible people. As a result, now there is a clear cut policy on them. Get caught operating one, pay a big fine.