Y'see, SONY are the main driving force behind the inclusion of DRM within their own stocks of commercial CDs. Yet many years ago, SONY was also the driving force (and the Copyright holder for the design) behind the Compact Cassette Recorder.
Back in the 70s, SONY was proud to have the patent for the Compact Cassette, and subsequently the patent for the first RECORDABLE Compact Cassette machine.
In the 80s, SONY was the forerunner and patent holder for the Compact Disc. They initially felt it would help promote sales of the Compact Cassette market, because car owners would record their shiny new, crystal-clear CDs onto Cassettes to play in the car. That way SONY got the best of both markets.
However, with the advent of the new powerful home computers in the 90s (the ones equipped with CD-ROMs) there came upon the face of SONY, a dark shadow. Users could digitize their CDs WITHOUT using (or promoting further SONY sales) Compact Cassettes, by burning perfect digital copies of one CD onto another CD without any more money heading into the SONY coffers.
THAT, and no other reason, is what brought about the furore that we all recognise as Digital Rights Management. However, it is very difficult for anyone to be prosecuted for using P2P networks because of the historical relationship between the consumer and SONY - who originally promoted the copying of copyrighted music for financial gain. ;)