There's a big difference between a subject noticing you're photographing him, and posing the subject, Omer. That's the main bitch about Doisneau as a street photographer. He posed a lot of his stuff and then pretended he didn't. The classic is Le baiser de l'hôtel de ville. The actors he hired for that shot discovered how much money he was making on it and sued (unsuccessfully) to be paid more. With the lawsuit the cat was out of the bag.
In your first example there's no reason to believe the people behind that flag realized Frank actually was shooting a picture. The guy on the right can't even see through the flag. In the second, HCB definitely posed those prostitutes. So what? He never claimed he didn't.
Bottom line: It depends on what you're after. Gregg's cute, giggly girls know they're being photographed, and the result is a picture of some giggly girls cracking up at being photographed. In the second shot we can see clearly that the guy knows he's being shot. So what?
Yes, most really good street shots are made without disturbing the scene. That's a different kind of thing from what Gregg's doing here.
The lensculture link starts as a slide show with the flag pic, but the one I refer to is the second picture, one you should know well. It is on the cover of
The Americans, as I said in my initial comment.
I didn’t say anything about posing, though I’m not opposed to it in street work. Don’t challenge me on this, it is a locked disagreement that I won’t open and a waste of your time.
As for the HC-B pic, can you give me a link to where he, or someone (not you) who is an expert on HC-B, claims the women were posed? I’d appreciate that.
Photographers find their own way of working, and the proof is as they say. If someone wants to do street work, they’ll find a method that suits them.