Maybe this is unique to where Voyager and I live, but whenever an organization I belong to is using other paid services of the hotel, such as catering or hotel rooms, the hotel comps the meeting space as part of the contract. (I’ve helped plan these things, so I’ve seen the contracts.) The key is “other paid services”. If an organization only uses meeting space, without other paid services, it has to pay for the space.
A lot of restaurants with banquet rooms do that, as well; as long as you’re buying your meals from them (and I’ve yet to go to a restaurant that allowed outside food), the space is yours to use.
I don’t think it is location dependent - I’ve been involved when we were in North Carolina, Texas, and both Northern and Southern California, and it is the same deal. Meeting space is very attractive, and many hotels would have it be vacant during the day if there wasn’t a conference booked. You do pay for room set up, so it is not entirely free.
BTW, the first thing we do is get insurance on event cancellation, through IEEE for us. I haven’t seen the policy for a couple of years, but I’d be surprised if it covered either cancellation due to low attendance or cancellation due to politics (like the AHA example.) I wasn’t on the steering committee then, but we had a meeting 6weeks after 9/11, and those who were on were very nervous.