I'd say plethora is wrong at least in US. Ridiculous retroactive copyright extensions would be my main gripe (though I doubt Grooveshark has any works that are about to become public domain). Or creative accounting that makes artist indebted even if their song is sold in millions.

Also I have a suspicion that most people use Grooveshark as a form of radio in such way that it doesn't really feed on artists main source of profit (CDs and concerts).

However don't take this out of context I still dislike lack of any mechanisms for artist reimbursement.