Networks were not like they are now. In most cases individual stations each had separate owners (or one owner had two stations as was the maximum allowed) so AFAIK the managements of each station would essentially meet as a network “committee” and vote on giving new shows the go ahead and program acquisitions and I guess each station then contributed financially as per their market size. I don’t really know for certain.
This was the sort of thing that got Neighbours dumped by Seven. HSV7 were pushing for it to continue (and its ratings were pretty good in most places except Sydney) but reports go that ATN7 management did a ‘divide and conquer’ approach and quietly convinced the other network channels to vote against it, convincing them that the Seven Network were better to continue with Sons & Daughters and A Country Practice (both Sydney-based soaps) and that the network did not have enough money for a third soap.
So the show got axed and we all know what happened then.
Apparently Seven in Sydney and Melbourne did not always have an easy relationship (HSV owned by the Herald and Weekly Times, and ATN owned by Fairfax), and same with the 0-10 channels in the 1970s (ATV0 owned by Reg Ansett and TEN10 owned by United Telecasters).