Hippies.

So, I work with a lot of hippies who listen to jam bands. I listen to a lot of the same older music as them, but we have different taste in a lot of newer music.

Hippie music was the counter-culture music of the late 60s and early 70s. As the 70s wore on, the hippies burnt out or sold out and punk became the music of the far left. Punk evolved into and influenced many other genres of music -- some which acclimated to pop-culture and some that didn't. I would say that the current manifestation of counter-culture music is noise and experimental music.

To me, jam bands today are not part of the counter-culture although I would assume they are left-leaning and still like taking drugs and partying. However, the music that they are playing is about as controversial as a 2-piece bathing suit.

Music evolves and musical tastes should evolve with it.