On one hand, the pre-programmed set lists would bug me after a while, so I can empathize with the coworker for wanting to listen to something else. (I don't listen to commercial radio anymore because I find the repetitive programming to be bothersome.)
On the other hand, it sounds like she is turning her music up so it's drowning out the pre-programmed music for herself, which is creating a problem for others around her. Not okay, IMO. This would also bother me tremendously. I'd have trouble concentrating.
I agree with amylouky that headphones or earbuds could be a solution. That or she needs to turn her music down. I'm not sure she should control the volume of the pre-programmed music. That strikes me as somewhat entitled. I'd go to her first and suggest some compromises with empathy for her situation -- she must be tired of the piped-in music. If she refused to compromise, I'd take it to a supervisor. Depending on the supervisor's response, I might bring in my own music and headphones.
Another solution might be to let everyone take turns throughout the day to play their preferred music.