Photographer's are screwy. We see visually, while most people experience life through attention or emotion.
This became clear to me working with writers at newspapers: a writer would, for example, want a photograph showing "interaction" between people, but the narrative form of "interaction" is based on what people feel inside, which is what writers write about. When people "interact," it's about the focus of attention and emotion on another. That's not necessarily visual.
People engage with emotion and attention.
Instead, for a photographer "interaction" is about movement. It's about the visual relationship between subjects, and how those subjects intersect in a three dimensional plane in a way that not only can be captured with a camera in two dimensions, but the quality of that intersection such that it visually indicates "interaction" if you don't know who the subjects are or why they're interacting.
But photographers often see those interactions as design elements.
These are two distinct ways of looking at the world, and it's very important for all photographers—but especially street photographers—to appreciate that almost everyone except us engages in a world of attention and emotion. Very rarely is a non-photographer subject aware of, or able to appreciate, their existence as a visual element. (Models are an exception, which tells you how rare it is.) Instead, when almost everyone but a photographer looks at someone else, they are looking with attention and emotion, and assume the same when someone looks at them. When a photographer looks at somone, the photographer is usually looking at symbolism, action, representation, contrast, color, luminance, or any number of things which don't have to do with the subject as someone of personal interest.
Subjects can't perceive their function in a frame.
As I say, these are two different ways of looking at the world, and this is the explanation for why street photographers are often harassed and assaulted. The solution starts with being aware of the way in which you are evaluating your subject and by not expecting them to understand or empathize with it. All the world's a stage, and the street is a public venue available to all—including photographers who are creating their art. But having empathy for your subjects and realizing that the intense attention of a camera will be interpreted in a very personal way is a good start. When in doubt, do as Henri Cartier-Bresson: tread lightly and work fast!
It's nearly impossible for a subject to think of being part of a scene. No one but the photographer sees the moment though the camera.