I assumed it was because of sponsor commitments, but it just sounded somehow odd.
I had to deal with a similar issue in religious broadcasting when I was younger because all the religious broadcasters were ‘sponsored programs’.
A controversy was brewing over religious schools in Nebraska with people under arrest and a school operating in defiance of the state.
Our ‘special reports’ had to go in unsponsored time or had to be inserted as brief announcements between sponsored shows.