Interesting conversation based on 19th Century infrastructure and demographics. Yes the State governments have hindered progress and perhaps putting an argument based on 19th Century issues at least places it in their time scale for decision making.
!!!But Wait !! There is an "Elephant" in the Room;and a large one at that.
A Recent post in this forum Highlights Infrastructure Australia in its 14 Feb 2019 report giving as a high Priority Initiative
"Preserve corridor for East Coast High Speed Rail
" . The route preserved will determine how existing and planned transport systems will develop; on both coastal and inland corridors. and its route will impact al lof Casino, the Tweed and the Gold Coast
Ok I can hear the moans and groans already but now the second Sydney Airport is going ahead this project becomes top of the nation building tree.
Perhaps even Australian Politicians, and it will be a federal initiative, can recognize the rapid development is already happening along the coast between Brisbane and Sydney and delay in Preserving the corridor will be extremely expensive.