In an ideal world, as photographers, we would be able to do all of our work with a single, compact, fast lens. In reality, even the most minimalist photographers will carry at least one other lens, depending on the situation.
There are some Magnum photographers who are well-known for carrying a minimum of equipment. David Allan Harvey is famous for carrying just a 35mm or 50mm equivalent lens. But even he will have another lens with him. He has cited that he sometimes will carry a 35mm with a 28mm, or perhaps a 35mm and a 50mm.
Henri Cartier-Bresson, famous for shooting the majority of his work with a 50mm, also carried a 35mm and 90mm, with a second M body, in a tiny bag. In the 70’s, which was his last active decade as a photographer before he devoted himself primarily to sketching, he replaced the 35mm with the petite 40mm Summicron.
Another Magnum photographer who didn’t bring that much gear with him, but still had a selection of three lenses, is Josef Koudelka. During the 80’s, he worked with 28mm, 35mm and 50mm lenses. I saw him on the street with a 35mm Summilux on a battered old Leica M4, and on a separate occasion with the same 35mm and M4, plus an Olympus OM film body with a 50mm as well as a Fuji panoramic film camera.
It’s great to be able to shoot with a single fixed focal length, but having another lens or two opens up the possibilities on the street considerably. And as long as you have a small bag to carry the extra bit of equipment conveniently, it can be quite easy to carry this gear, even on a daily basis.