Could you tell me about fly-in communities in the United States?

I just learned that there are some places in the U.S. where almost every household has a plane, for example around Anchorage, Alaska. From what I read, it’s because the area is so sparsely populated and building roads is very expensive, so having a plane makes getting around much easier.
Are small planes just relatively cheap in the U.S., or are people in those areas generally quite wealthy? Are there other fly-in communities like this in the U.S.?