Not arguing that. There is a courtesy line most of us wouldn't cross, but it's just not a law. A lot of people think it's illegal to take photos of their kids without their permission, but there are plenty of photographers that like the candid shot, so they don't want you to pose. We recently had a police officer killed in the line of duty. I took quite a few photos of kids holding American flags and signs supporting the police. I always walked over and told them it was for the local news and the Police Department. It helps that I have a big camera and lens. Trust me I agree, it can become creepy quickly.
As far as an accident, I don't normally want those photos, but sometimes we take them. It can show the police and EMS in action. I also understand if someone is upset with me taking photos when their lives are turned upside down and I try to be sensitive to that. The police actually drove me through the Bastrop fire here in Texas and even though it was horrible to see people losing their homes, it also needed to be documented for history. There's always a gray line, but for me I try to be as kind as I can.
On the other hand, if someone storms up to me and wants to have a "come to Jesus" conversation with me for photographing their company plane, they've pretty much guaranteed I'm going to take a lot more photos than I had planned! I know my rights and I won't have them walked on.