Won't rights owners try to sue Google the same way they whine about lyrics sites?
I imagine Google can offer better terms and/or soft-velvet glove (traffic) then Rap Genius.
I only bring up Rap Genius, because they seem to have taken over (admirable) as the foremost lyrics site.
[1] http://www.nytimes.com/2014/05/07/business/media/rap-genius-...
How do you know that Google hasn't acquired the rights to use the lyrics for promotional purposes for sale of the song and the Google Play Music service as part of the whole package of getting the songs on Google Play in the first place?