Greeting people is extremely overrated . As a child adults I knew would make a big deal about children greeting adults when they entered a room of adults. I always thought that was stupid, because the adults never spoke to the kids first. If I don't speak to you I'm rude but if you don't speak to me it's ok, how does that make any sense.

As an adult I greet people when I want to, and if I don't, I just don't.