Because they've been conditioned to be disconnected from one another. They've been conditioned to stand down, when they should stand up. There's no common bond of moral certitude or binding chain of honor amongst them anymore, and so they sit mute.
Long ago, a rabid gang of heathens running amok like that, would have been rounded up, and strung up in the town square by the local men. And no one would have had to tell them to act, either. It's just what was done.
A sense of common decency, and the courage to stand up and protect ones community, is just one more thing that we in the Tea Party wish to restore in America.
Anyone with any assets would end up stripped and left naked by our legal community. That's just the way it is.