My GF likes them. We encountered them playing near Bürkliplatz on Easter Saturday, but the pigs came along and harassed them before I got a chance to find out the names on their CDs.

Is busking illegal in Switzerland or only in Zurich?

If yes, it's a shame as busking gives so much character to cities such as Barcelona and Vienna.

Can't speak for ZH or other large cities.

But, in order to perform (or beg) on the Bahnhofstrasse in Buchs you must
have a permit from the Gemeinde (City Hall).

If you didn't - no matter what size the city is - you'd have lots of scum on
the streets. Switzerland doesn't want that kind of "character".

The homeless of Berlin have organized themselves and sell a kind of
newspaper prepared only by the homeless and sold for cents. That is
registered and allowed. They ask if you'd like to buy one, if you shake your
head, they walk away... no stress.

As for the OP, sorry - I do not know.

It's banned in public transportation (at least in Zurich anyway).

If they're the group who dress in Latin American costumes, it's very organised as you can find similar groups in many countries, including Cyprus and Malaysia.