Neo, the problem with any solidarity, like the fmdac, is that our numbers are so small in this geeky niche hobby, that there's not enough $$ to hire high-powered lobbyists. So it can't be compared to the NRA, for instance, since we have so few in our ranks.
And I'd also be careful of them, or anyone, going and "lobbying" any more than absolutely necessary (to fight something actually proposed, or already existing). Because if you or I run around trying to "pre-empt" any such rules, then sometimes it back-fires. Sometimes it can cause the VERY ATTENTION you and I sought to avoid, in the first place. Doh!
.... having to ask permission isn't freedom.
And be aware: You don't need to "ask permission", where it's not forbidden/prohibited, in the first place. If there weren't a rule at whatever place you have in mind saying "no metal detecting", then presto, it's not prohibited. And then no, you don't need "permission". No more so than you'd need permission to fly a frisbee, for instance.