.... There is a clause that implies that permission may be granted by Park Authorities under certain circumstances.....
We can all agree that duly appointed LEO public-officials (cops, rangers, city gardeners, etc...) do indeed have some latitude to administer the duties they have. And it's impossible to "make laws" for every conceivable thing that *might* come up . So there are general catch-all type laws, such as laws that forbid "annoyances". Or "blocking sidewalks" (ambiguous on the amount of time you can stand there, etc...). So that a cop can use them to enforce, as is needed, to break up a street party, etc....
And in similar fashion, a ranger could come up to your camp site and tell you that your boom-box is too loud (d/t he might think it bothers your camping neighbors). But no one would think for a minute that you need to "go get the ranger's permission to play your boombox", eh ? The fact that, yes, he can come tell you to turn it off or turn it down (fully within his power of authority), does NOT mean A) it's wrong to listen to boomboxes, or B) that you needed his permission to turn it on the first place, etc...
So I am convinced that a lot of these "inquire at each kiosk" or "with permission from the ranger" type verbiage, probably STARTED as the answer to the "pressing questions" that md'rs posed a few decades ago. And the "safe" answer was always "ask at each kiosk" or "with permission". And then pretty soon, it just makes its insidious way into the actual law (and now exceeds simple "commentary" and has now become actual "code").
I admit that the MA was seems to be more than just "commentary", but I betcha it started as nothing more than "ranger's ability to tell you to stop", to eventually being "must get his OK beforehand". And I still wonder if this is one of those situations where you'd be hardpressed to find a ranger who even knows or cares about this [Unless, of course, scores of md'rs go asking, so that they are perpetually looking up and seeing this]