They go grocery shopping and stuff. Dr. Yang sent them to town to network with local businesses to make a commercial for them (for free) as part of their video training (so they can make instructional videos, I guess). They teach classes up there to locals; I think it's just kids (well, I don't think that's a rule. I've just read about them teaching kids). Then sometimes people from other YMAA places will fly in and they'll all train together.
They're really not as isolated as people think.