What is your opinion about street photography?

I do photography as a hobby and I had this discussion with my girlfriend about Trevor Wisecup's work (amazing street photographer imo) and she doesn't like the way he works. For her, he's just stealing intimate moment from people. I personnaly get what she means but imo if it is done in an artistic way, there is nothing wrong about that.

We are French, and maybe it's a cultural thing. In France, most of us are pretty discreet and don’t really like being photographed, etc.

What is your opinion about that? And is it ok in your country / culture to take photos of random people in public areas?