Lou,
As for the AMA securing fields you are only partly correct. While they may not be the ones who start the process without flying site insurance coverage there would be far fewer places to fly. Even a public field such as the Basin is only available for sanctioned events because of AMA insurance held by the local clubs.

While they may not be a lobby group they have in the past helped work out frequency sharing policy with the FCC and have been active in recent issues.