I think it mostly comes down to the intent of the photographer as they make the image, and I think it's accurate to say that a lot of street photography is taken by relatively inexperienced photographers who are still getting their feet wet - they haven't yet developed a firm ethos to guide their shutter finger. It was the same for me when I started out.
When you look at the work of someone like Salgado, he photographs people often in desperate situations but his philosophy is to show the strength and dignity of the person within that situation. His photographs are all celebratory, and it's a conscious choice. It doesn't make it true, but that's how he chooses to present his subjects.
Less experienced photographers are often still stuck on the observational, they see someone doing something and think that it's noteworthy to record it; "I'm not mocking them, I'm just recording the scene and it's up to the viewer to judge". No, it's up to the photographer to make that call before the shutter is even pressed. We tell the viewer what to think and what to feel, that's our job as photographers. Every photograph we make is a reflection of ourselves. And I think it's absolutely fine to take a photograph that doesn't show someone at their best, we're all struck by different things and a lot of the time we just want to record the moment and how we feel at that time. What we ultimately do with that photograph is what defines us.
Was it Avedon that said something like every photograph we take is a self portrait? And all photographs are accurate, none of them are truth?
We get maybe 1/250sec to reveal something about someone or to make a statement about someone in a particular situation. It's the easiest thing in the world to take that fraction of a second and turn it into a narrative, true or false, which can define that person (sometimes permanently). My take is we need to give people the benefit of the doubt, but we do that with framing and pressing the shutter only at the time when the expression on their face, or their gesture, supports the story that we want the photograph to tell.
Any time someone says: "I just recorded the scene in front of me, that's how it was" - it's just a reflection of their inexperience. I've never met an experienced photographer who was unaware of the impact they have on their own photographs.