ORIGINAL: Hossfly
stl:
"....but not required for a flying site unless the site is owned by the club."
Keep that old wishful thinking concerning public sites cannot require AMA to yourself as I know the Harris County, TX park system require AMA, and unless big changes have happened the same applies to the RC sites in Cook and Lake counties in the Chicago area. There should be someone from one of those clubs that can confirm or deny what is currently in force there.
As soon as one person threatens to sue for not being allowed to fly without having to join AMA, those localities will change and accept proof of other forms of coverage.