To answer the question at the head of this thread, the answer has to be "No". However, it sounds as if the ones being discussed are neither artisits nor mimes.
   Mime is not exactly my taste, but to learn to do it properly is bloody hard work and requires a great deal of training. One person who actually did it - and was an excellent street performer in his day - was the Australian comedian Glynn Nicholas. (You Aussies know him from the Humphrey B Bear Show and The Big Gig).
   I think the people being described by previous posters could better be described as talentless pests. I regret to say that I have seen more of these than I would like to have.