I guess I'm starting to see more where they are coming from
"ABC News" is essentially "on" 24 hours a day - on TV, radio, social and digital. So that one brand is for all platforms.
The TV channel will say "you're watching ABC News across Australia", the radio station will say "you're listening to ABC News" (obviously you are on radio) and when pushing to the 7pm broadcast it will perhaps be "ABC News at 7, on ABC"
it makes sense that the radio, tv, social and digital networks which are on 24 hours a day get the "master" brand of ABC News - and the 7pm broadcast which only runs for 30 minutes is a brand extension of that.