Jason, Galaxie 500 aren't exactly a relevant, buzz worthy band, so that's just kind of silly thing to say - as far as googleing them. However, I really like your idea of the donations icon in these streaming services. But what then would essentially set them apart from Bandcamp and pay what you want?
Why? Google can find their music
just the same regardless of their relevancy. Scale, mainstream/all artists, and putting the places to pay for music in front of as many people as humanly possible. If I could listen to the new Andy Burrows album for "free" whenever I wanted via Rdio, and I knew I could drop him 10$ or something personally ... I think I'd do that instead of buying the digital album. And I'd probably still get it on vinyl later as well.