Don’t kid yourself. Public radio is commercial as well. They just call it something different because they are not-for-profit. Why do you think you hear the announcements like “All Things Considered is made possible by a gift of the XYZ corporation, and then 20 seconds of information about what XYZ Corp. sells.
Occasionally, they are paid in trade. I remember my friend worked at KJAZ in Alameda, and instead of money, he was given the value of a few meals at a local steakhouse that advertised on the station. He wasn’t happy, since you can’t pay bills that way.