Correct AMA is not required to fly R/C in the US however there are a few things to remember.

1. Flying at a non AMA ( FRIA ) site with a model over 250 grams you are required to have a RID module.
2. Flying at a non AMA site, you are required to establish and maintain a safety line to keep non participants from entering your flying area.
3. You are required to follow any local laws pertaining to flying models at your location of choice.

Regarding AMA clubs operating on leased public property.

When an AMA club leases the land from the city, county or state they become the tenant of that property legally and that gives them the right to establish rules as they seem fit. In most cases the lease agreement will dictate that any persons flying at the site must have AMA insurance to do so. The lease also gives the club rights to have anyone removed from the property for any reason, AMA member or not. Most clubs do allow any AMA member to fly as a guest but it’s best to contact a club officer prior to inquire about their guest policy. Very few will ask you pay a small fee for day use or require an established club member to sponsor your visit.