I have had a couple of run-in’s with people and know it's really pissing into the wind to try and educate them as to the shooter's right to make photos in most situations in public. It's especially difficult to educate them when you're shooting breaking news of a violent event such as a shooting or auto accident.
I was taking pictures of my granddaughter at a local eating place and the people in a booth to tables away had the waitress tell me to stop, it bothered them. Go figure.
Could be that some folks have seen “authorities” and newsies run amok too often. Might be a good idea when doing more than taking snapshots with a handheld camera at a scene that isn’t an emergency, to announce your purpose to the others present.