I also don't understand how people can have the same outrage for these kind of shootings (e.g. armed with a knife) that they have for shooting an unarmed person

I also don't understand how people can have the same outrage for these kind of shootings (e.g. armed with a knife) that they have for shooting an unarmed person at a traffic stop, etc. At the point where someone decided to wave a deadly weapon around at others, I think they've knowingly forfeited their right to personal safety. Doesn't mean you should just shoot them if they are 15m away, but it does make me feel a lot less bad if they get shot in a position where they could have easily killed someone otherwise.