My two cents on the topic is that HSR from Melbourne to Sydney should implemented as a series of incremental upgrades, rather than a single megaproject.
It wasn't done as single megaproject. Instead, it was done in small segments. A bypass around a town. A section of road between two town upgraded to dual carriageway. Eventually, over 40 years, the whole road was upgraded.
We should be doing the same thing with the train line from Melbourne to Sydney.
The Australian Parliment could do with a huge influx of people who have worked in deeply technical fields. People who have 20 years experience building bridges, designing mining equipment, managing road building, running a Hospital Emergency Department, coding a billing system that works, etc…
Our current crop of perception managers (aka bullshit artists) don’t even know where to start when it comes to actually getting the stuff that needs doing, done!