You're wrong about this. There's a lot of very good banjo and fiddle type music that definitely attracts more of a lefty crowd than a right wing crowd. The combination of the folk music hey dey in the early 60s with the roots based origins of rock and roll make it a perfect fit. Bluegrass music attracts plenty of Subarus and Volvos. Someone else had the right idea. They need to make a record, or do a tour, sharing the bill with a couple of old lefty hacks. Neil Young would be perfect. Neil Young and the Chix would draw a totally left wing audience.
I realize there are some Pete Seeger holdouts out there, but they are small potatoes compared to the huge audiences the Chicklets were drawing a few years ago. Despite what they're now saying, they were going for a larger audience, not a few thousand people at some left-wing bluegrass bash in upstate New York.