As a street photographer, I think like others have mentioned, I need to be mindful of not publishing a photo that I could construe as embarrassing or similar.
I think Western culture's emphasis on individualism (which I actually like on the surface) gets to our heads and we take it too far, thus making us take ourselves way too seriously. What really is the harm of a candid photo being taken in the public? The real boogeymen are going to be far more discreet than shooting from less than a meter away with a 35mm lens. Yet we go after the guy who isn't trying to hide anything. I get it from an instinctual level, but it is very illogical.
Luckily, most people are amused or flattered or intrigued or are slightly put off but just go on with their lives anyway. Or they don't notice. Still there are those with a higher state of self-importance who will get in your face occasionally.
Ah, the classic "why not just ask for permission?" I think if we as street photographers could get what we wanted out of our photography asking permission, we would probably solely do just that. But most only dabble in what usually amounts to street portraiture; when you ask permission, people are suddenly very aware of their being photographed where they otherwise may not be or may have only realized after the fact. Because of this, people tend to put on a face when they know they're being photographed and it isn't as genuine and candid and real. That's what street photography is about -- documenting real life, not posed life. We have our Instagram selfies and Facebook albums for that.