Agreed. There's no place for racist slurs on HN, especially when they're posted from behind anonymous usernames. It's often the kind of thing people wouldn't dare say under their real name if their livelihood depended on it ;)
Has nothing to do with that. If someone is looking for something, they can find it anywhere. If you want to say "prevalent in [place name]... etc" The emphasis is on the tech culture. The factors are multiple. Parallel: Do you know about chauvinism, etc.?