This argument has been going on for along time - The full text of (the Elizabethan) Harman's Epistle to the Reader from
Rogues, Vagabonds & Sturdy Beggars is here. Also look at the link (at the bottom of the page) to the review. There was a 1531 regulation passed by Queen Elizabeth - which is where the term 'Sturdy beggars" come from.

It seems there is some agreement in this current thread about the intent and (musical for musicians cause this is a music forum) ability of the performers. Strictly speaking, being paid by a 'patron' such as a business or a council means that you are not a real busker.

This Google Search also brings up the group called Sturdy Beggars. It also currently finds a copy of the original regulation.

Robin