If you want to fly at an AMA chartered club (benefit of membership), then you need to be a member of AMA.
P-51B,
Most of the clubs I know of are AMA only and since this post was made by a beginner who will most likely need to learn at the local club. WHICH MEANS HE WILL NEED AMA or NO flying...
As far as private land you're right I've been flying on and off for 18 years I do have my own private land and I've only been a AMA member fro 4 of the 18 years.
Thing is folks flying all alone gets boring and while I'll fly at my place without insurance I won't let others! Simple fact it is to risky for both me and them liability wise.
But maybe P-51B you know of an other way the majority of beginners can learn to fly in their areas without having to pay an instructor or join the AMA.