If I want to play stuff from my music collection, I play it via bluetooth from the cell phone
Which requires having a cell phone that supports playing a music collection over Bluetooth. Among phones that I've investigated that are capable of doing that, they tend to cost more over time to operate on U.S. carriers than cell phones that just make calls and receive texts. Virgin Mobile, for example, refuses to activate smartphones on dumbphone plans, and the price difference between the cheapest dumbphone plan and the cheapest smartphone plan is over $330 per year. And that's why a lot of people still carry a separate phone and MP3 player.
This usually only happens when I'm on a long distance road trip in the boonies where there's no radio stations
There are lots of urban areas with no radio stations of a particular format. For example, the adult standards (Johnny Mathis, Frank Sinatra) station in Fort Wayne, Indiana, just switched to classic hits (60s-70s) last week because the Social Security demographic isn't quite as attractive to advertisers. And I still haven't seen a single station that's all Creative Commons all the time.