Curious Cat Question

Just recently saw director Cameron Crowe's latest movie, Elizabethtown. Not bad, quite entertaining actually (aside from a few questions rolling around my mind like loose marbles). However, what got to me was that it had a really nice soundtrack.

As this article says:

Crowe likens the music from 'Elizabethtown' to a 'great American radio station' - a perfect road-trip mix tape.

So my question is: why aren't you people playing more blues and rock and...?