>I suspect that a lot of the nice behavior on HN is because, for the most part, people value the community, and consider this a "professional" environment, and it's not a bad idea to play nice in places where employers/ees can see us show our butts.

People here also have made it or perceive that they are on the path to making it. They may think that housing costs are too high or the police are too violent or that outsourcing has been bad for the American worker. But we're by and large not without adequate housing, the target of police violence, or in the poor house. It's easier to be less outraged when you're sitting at the top of the heap.