In Canada we have the Model Aeronautics Association of Canada (MAAC) which is basically the same thing as the AMA and that has pretty high individual member and clubs fees as well. In both cases, I believe the cost is mainly due to the liability insurance provided to the individual members and clubs. Most homeowners insurance policies provide liability coverage for claims arising from the hobbies and sporting activities of family members, but I’ve been told that insurance companies only consider model aircraft as models while they are on the ground and once airborne treat them the same as full size aircraft. Many, if not most, models weigh at least several pounds and they can do a lot of damage if one has a problem. Flying without insurance is taking a huge risk and why every club I know of is a member of MAAC (or AMA) and why clubs only allow those that are also members to fly at their fields.  Anyway, I figured some may like to know why the membership fees were so high (they are actually quite reasonable considering what liability insurance costs for such activities).