Not only that, but anyone who does act may be opening himself up to all kinds of legal headaches and official harassment.
I have lost count of the number of news stories in which someone used a firearm in self-defense, only to have the police say something like, "Although it turned out OK this time, usually we do not recommend that people take the law into their own hands by confronting a violent person." In some cases, I read that the armed citizen is under investigation for possible violation of this or that regulation.
So the people who refused to intervene are just acting the way they have been told to act -- that is, like sheep. The authorities should be pleased.
Good post.