The AMA sets guidelines but the management of clubs is up to the clubs themselves. Some clubs are all electric, some all helicopters, others don't allow helicopters etc.... thats not the kind of things the AMA wants to get involved in, including who can fly there.

One point here, and it may be minor, but the AMA doesn't sanction fields, it sanctions clubs. As someone said, the only "AMA Flying Site" is in Muncie where the HQ is. You can fly, and by covered, anywhere you have permission and follow the safety code.