London

Where I live, there is no restriction (other than the standard policed ones) on using amps etc.
This means on a 500m pedestrianised high-street, every Saturday is 6+ separate people making noise.
It gets unbearable, because while one in ten is actually half decent, the other nine are cranking the backing track up as loud as possible to get some people paying attention.

I don't live in London, but am I correct in thinking that TFL made people do auditions for busking spots on the tube?
That seemed to be a neat way to improve the quality. And did make me laugh the one time I had to wait just outside a station, then realised that the busker was playing the most well known 30 seconds from Wonderwall over and over.