"...the music industry is economically quite small and unimportant compared to the computer industry."
For some perspective, the largest label groups in the "music industry" are owned by corporations that are bigger than Google. Universal: owned by Vivendi. Sony Music: owned by (guess who). EMI: owned by Citigroup. Not exactly small economic players...
So it would take all of Google's cash on hand to buy 1 player (assuming they could even pull it off). It isn't like google's market cap is something they can liquidate or even really make any significant usage of.
Sony bought out their equal partners, Bertelsmann, for 900MM. [1]. That puts Sony Music's valuation at $1.8B in 2008. Global spending on music seems to be around $26B.[2] Although it's difficult to project a valuation from that, it's not unreasonable to assume that any of the tech giants could afford to buy a significant chunk of the industry.
That'd be to buy ALL of Sony. Sony Music, Sony Pictures, Sony Computer Entertainment (which is mostly Playstation), and a not entirely incidental consumer electronics business. Sony might be worth more if you buy it and break it up, but this is exceedingly unlikely for a variety of reasons.
outright purchase is much less important than who can win a long legal battle. Don't sue someone who has more cash on hand than your net worth. it's dumb, especially when there's a lot of gray area around what specific license is on a particular song.
Furthermore, they use the RIAA as a sort of trial balloon to feel out the larger questions of digital rights and intellectual property. That is to say: they will fight with disproportionate resources to protect the comparatively tiny industry, because the implications if they win are far larger than music.
And should they lose, the labels are a minor piece of the pie, and they can send another pawn into the fray with an adjusted argument. (say, their movie or TV units)
For some perspective, the largest label groups in the "music industry" are owned by corporations that are bigger than Google. Universal: owned by Vivendi. Sony Music: owned by (guess who). EMI: owned by Citigroup. Not exactly small economic players...