At least, for me.
I believe that photographing is an art and that rangefinder photography is a much more complex, deep, engaging and direct technical art. No frills.
I often travel with two bodies, a Leica M and some other mirrorless or DSLRs. No one can give me that extra reason to raise my arm and press the button. Because despite the evolution of current cameras, a thousand aids that arrive to the photographer (what about the comfortable Eye-Af?) in the end, in travel photography, what is really needed are two dials and a button.
But you need above all discretion, a really silent shutter (mechanical, not digital!), which allows you to get closer to the subject without being invasive and intrusive, with minimum body and lens sizes and with wide apertures useful to shoot in any situation.
I can’t find none of these in other brands that give back, above all, the same quality of those German lenses that for over a hundred years have given us images with a unique three-dimensionality.
Those who seriously try a Leica M don’t come back. Or if it does, it’s to embrace definitely the rangefinder system. It happened to me in a recent trip to Africa to bring also a very advanced mirrorless camera with a superlative image quality, but that feeling, that extension of the arm that only my faithful Leica can give, was completely absent.
The sense of photography for me is to create a direct and filter-free relationship with the subject, being as less “present” in the shot as possible. Take a photograph without asking permission creates the risk of not having that “feeling” in the frame that for me is a reason to tell a story.
To deepen the approach to people on the street, I’ve already wrote this article.
If you just want to read something more about the technology behind the Leica system, I wrote this other article.
Finally, if you want to understand the reason for choosing the rangefinder, I wrote this one for you.