thanx for your support sky-pilot. And you say the "no" can be:
" .........
just because you've empowered them to do so!"
There's a lot of true psychology wrapped up in that statement! It works like this:
a) the mere fact you're standing there in front of them, asking them "can I do such & such", merely implies that they have the say-so (lest why would you have asked them, if you didn't feel like they had that right?) You might *think* they would have to back it up with something in an actual rule, right? But even in the absence of a specific rule, they can still say "no", simply because the premise of your question, is that they have the power to say "yes" or "no". Because if it were dependent on a specific rule, then ... heck .... you could have looked it up for yourself, without their input altogether! (city and county codes are usually available on-line). This implied psychology is not lost on the person you're asking. And if you object, and say "
but where is that written?", guess who's going to win that debate?

All they have to do is cite "no collecting" verbage, or "cultural heritage" verbage, or "disturbing the vegetation" bologna, etc....
b) Also there is a powerful implied psychology in the "asking" process that also sets you up for a probable "no". And it's this: The mere fact that you are there asking someone if you can do a specific thing, merely implies that something is inherently wrong, damaging, or evil about it, that you had to ask,
to begin with. Afterall, if there wasn't something askew, then why would you be asking permission? Ie.: would you ask to fly a frisbee? Ask to skip stones on the pond? No. Of course not. So then when you come in asking to do something odd (that they probably never gave though to beforehand) like this, guess what the implication is? Their mind will subconsciously pick up on this, that there must be something off or damaging,
lest you would never have been there, asking, to begin with. Thus another reason for the "no's" often-time.