I'm guessing that no one inside the train responded because they probably didn't see it. Believe it or not, people do care and they do respond. While waiting on a platform for a train at L'Enfant Plaza I saw a teenager run past me. Shortly thereafter some guy in business attire ran after him. The kid stole the guy's PDA and those of us who weren't trying to call Metro police ran upstairs to find a guard. Thankfully, a group of strangers surrounded the teenager and held him until Metro officers came and got him. When he was taken away in cuffs, everyone applauded.