fair enough on your replies. Here's a very long essay that gets to what you're asking about as well: https://theanarchistlibrary.org/library/peter-gelderloos-how-nonviolence-protects-the-state

Which "violence on both ends"--by which you likely only mean protesters, because we just assume that violence in natural on the side of police--are you referring to? The one where the taxi driver gets beaten after driving through a crowd? Or where the police officer is attacked after driving through a crowd? Or where police officers, in full riot gear, are hit with umbrellas after indiscriminately charging, beating, gassing the crowd?

I feel safe walking through a demonstration. I feel unsafe when the police are around. I also work with non-politically engaged professional foreigners, and they feel the same way about living in HK right now. That's the most meaningful comment on the violence of both sides, in my opinion.

Moreover, for your American example, non-violence resistance has always been accompanied by radical and/or violent opposition (for examples from two historical moments, John Brown and Fred Hampton). And either way, in the end, both MLK and Hampton were murdered for their actions, nonviolent and radical alike.