[dctoedt]

> I can just imagine what would happen if this occurred on Bart. You would probably either be ignored or people would record you on their phones and upload the video to Facebook.

That's not my impression. (Unfortunately I can't think of an actual counterexample.) I think people everywhere tend to help out. I imagine that when Americans are reluctant to get involved, they feel they don't know what to do, and they're afraid they'll be criticized or even sued for supposedly making things worse.