That the artists are being robbed by streaming. I don't know
As I see it, the whole concept is wrong. Why should a song played on the radio or streamed by services like Pandora be considered a performance? And why should royalties be payed for every listener? I mean, there's been EXACTLY ONE performance and that performance has been recorded ONCE. The fact that is being played over and over again should be irrelevant. And yes, of course writers don't expect money if I read a novel again, actors and directors get absolutely ZERO if I watch a movie more than once, etc.