Many bloggers and experts like to say that you should use wide angle lenses because they require being close to the subject. This makes street shooting a “fair” game. It seems dishonest to use a telephoto by hiding from a distance.
Hunters have the same debate when choosing a weapon. They will argue that it is valiant to select a tool that will give their victim a chance to escape.
However, we are photographers and our goal is to make great images. We are not in a contest with people on the street or with each other. The choice of lenses is governed by artistic considerations, feasibility, or convenience, not by some superficial notion of machismo.
Often I use lenses from wide to short telephoto, including small zoom. On occasion I have fun with my old long telephoto 60-300.
I don’t toggle lenses during shooting. My choice is based mostly on my current mood and situation. If I am in doubt I use a “normal” 31 mm (with 1.5x crop factor).
I don’t use a long telephoto because being far from the object (using small view angle) makes the depth of perspective compressed. But sometimes this compression is an important part of the composition.
Wide angle lenses allow the photographer to be very close to the person. Photographers can invade the personal space of the subject before getting a chance to use the camera’s viewfinder. This may require shooting from the hip or belly. Do not frame tightly in order to have latitude for rotation and cropping.
Use any lenses that you think are most appropriate for your situation. Don’t concern yourself with artificial rules that many candid street photography experts try to push.
Related topics
Candid Street Photo 
Long lenses can flatten an image. The point of the candid shot it to invite the viewer into the reality of the subject. A wide angle draws the viewer into the photo and makes them almost a part of it. This is subtle, but can often be the difference between a good shot and a great one.
I’m one of those who only shoot with wider angles, but that’s a choice I’ve made because it suits my vision. The rules some togs try to imply on everyone is rather useless if you put the result before the gear. If you get the results you want with tele lenses I see no point in going wider. The only thing I have against it is that many of those images tend to lose the feeling if urban context. (But that doesn’t means that it’s impossible to use tele – just that I think it is more difficult according to my vision. And my vision is not a rule 🙂
Regards
Jimmy
Well said Jimmy!
I know that your favorite lens is 21mm.
What do you think about post – Candid street photography in Morocco with Pentax K-5 and 21mm f/3.2
That´s what I´m talking about! 😉 The wider angle includes more of the background. But it is also obvious that is doesn´t work that way in all situations: your first image, where the guys have a wall/doors close behind, could probably be done with a tele to. Except for that the low angle, of course 😉