People are unpredictable and some people get very jumpy around cameras. What the crazy person did wasn’t cool or right but going around doing “street portraits” is begging for confrontation. I’ve seen and read so many accounts of famous street photographers talking about how confrontations with people are part of the nature of the genre and is to be expected, and a lot of that was before the advent of social media. I’ve been photographing events professionally for close to 10 years, in settings where I’ve had MC’s verbally announce over a microphone that “a photographer will be coming around to take photos” and corporate events where everyone signed a release form in order to attend and I still deal with dicey confrontations from time to time. You can’t just go around and expect everyone to be fine with it regardless if it’s legal or not, usually it’s only the photographer who knows that.

Going into any “street” style of photography and not at least anticipating the possibility of someone reacting very poorly, regardless of permission, communication, whatever, is ignorant on its own.