I have never regarded it as so - and neither have most of the buskers I know. In fact usually when one person steps forward to give money, others often follow. So it usually goes down well with the busker who is pitching.
By the way, thumbs up to Eliza for both what she did and wrote. Yes, a lot of people see buskers as people on whom they can offload their aggression. This mentality has a lot in common with a lot of "---isms". The aggressor needs someone to feel superior to, so they are wantonly cruel or rude to someone else - preferably someone who either can not, or will not retaliate. Cruel and upsetting as this behaviour can be, it usually tells us more about the aggressor than the intended victim. Acts of simple, intuitive kindness can do a lot more good than many people realise at the time.