I remember listening to WFMU's station manager recount one of the times he had to fire a (volunteer) DJ: the DJ was selling ad time on his show. He got away with it for a while because his show was not in English.
It seems that ads were also a motivation for the long-running show JM in the AM to leave the station.
> WFMU, licensed as a non-profit radio station, adheres to the guidelines of charitable and non-commercial radio. With the move of ‘JM in the AM’ exclusively to NSN, the program, its host, its content and its reach will be allowed greater creative flexibility and sponsorship opportunities. [1]
It seems that ads were also a motivation for the long-running show JM in the AM to leave the station.
> WFMU, licensed as a non-profit radio station, adheres to the guidelines of charitable and non-commercial radio. With the move of ‘JM in the AM’ exclusively to NSN, the program, its host, its content and its reach will be allowed greater creative flexibility and sponsorship opportunities. [1]
[1] http://www.nachumsegal.com/historic-jm-announcement-made-mor...