Probably not a universal rule that the oldest chooses the radio station, but Japan used to have a strong culture of age based seniority and social hierarchy. A traditional Japanese introduction involves a slight verbal dance around sharing your age and profession, so the meeting parties can determine their relative social status and what type of honorific language may be appropriate for each to use.

I think seniority has become a bit less of a factor especially for younger generations who are starting to ease away from some of the more rigid hierarchies.