Yes they are "considered" public airwaves and being such they are "considered" to have to serve the public.
However, they do have leeway in not airing certain commercials and they have done so. Political campaigns perhaps not. However, the notion that these are "public" airwaves can be challenged. So that's arguable.
There's not really much legal basis to the concept of public ownership of the airwaves. It's just been repeated so often without examination. When the Radio Act of 1927 was passed Congress specifically deleted a House-passed “declaration of ownership.”
A co-author of the Radio Act of 1927, Sen. Clarence Dill also said “The government does not own the frequencies, as we call them, or the use of the frequencies. It only possesses the right to regulate the apparatus. We might declare that we own all the channels, but we do not."
Even the Congressional Research Service, which conducted a study of the problems raised by proposals to assess fees from broadcasters for use of the spectrum, concluded that “the notion that the public or the government owns the airwaves is without precedent. We find no case that so holds."
Supreme Court Justice William O. Douglas...
...debunked the argument that the government can control broadcasters because their channels use airspace by comparing broadcasters to people who speak in public parks—like the airwaves, also in the “public domain.” He added, “Yet people who speak there do not come under government censorship.”
The spectrum is there, whether we use them or not. So the public does not own them. Govt is there so ensure they are used in an "orderly use of the electromagnetic spectrum so signals won't crash into each other, and clear communication could be impossible."
The area needs reform because too much central planning has entered in here and the public can benefit from reforms based on freely transferable property rights. But that's another argument.
The public's recourse is to change the station.
http://www.broadcastingcable.com/new...ves-myth/75018