I mean, obviously artists could opt out (and tracking them all down for back catalog perms would be a nightmare - I'm not without sympathy for the effort involv

I mean, obviously artists could opt out (and tracking them all down for back catalog perms would be a nightmare - I'm not without sympathy for the effort involved) but going forward could they really not set up a default agreement? The fact that they DO release some stuff commercially seems indicative it's entirely possible. Glasto is indeed another great example of audio tracks I'd gladly pay for - funnily enough though by the time the BBC takes it's coverage down some valiant internet person has stuck what I want up on torrents.