The point is that the musicians have already been paid for their performance by the BBC or whatever broadcaster is transmitting the music. How, exactly, can it be justified forcing people to pay for something that has already been paid for on their behalf? You are listening to a broadcast by a public service broadcaster. You are not broadcasting a performance.
actually the musicians do NOT get paid by the broadcaster*, that's why the PRS is there – to collect royalties on behalf of the artists.
I assume some of these rules go back to the days before magnetic tape allowed pre-recording of shows and, ultimately, the multi-tracked records (or whatever you want to call them) that we all listen to these days.
*unless booked to perform on a particular show by the broadcaster, but that's another issue.
Surely by playing their music in my shop I am 'advertising' it for them? If no one hears it then how can they decide they like it and go and buy it ( or download it for free…)!
you're only advertising it if you (or the broadcaster) tell people what they're listening to and where to get it from