I only meant cost relative to HSR track. Estimates run at about $40-$50 million per km of 500kph maglev track for construction, which would put Melbourne - Sydney at about $50 Billion, give or take a few bil for land and such, much of it could be built directly over existing rail. The Japenese SC Maglev needs straighter track though, although in reality it's speed is not really that much greater than the Chinses system to warrant the extra cost and restrictions.
You really think those facts have not been discussed over Cognac and Cigars the last twenty years. Certain business people lobby governments to keep high speed rail off the agenda.
In another view, look at the grief HS2 is giving the UK.
This is the real issue in Australia going back to facilities. Certain nameless companies thrive on maintaining duopolies by restricting access for competition to expand. This occurs in all fields from telcos to aviation and supermarkets. One master company rules and lets one or two other companys expand enough to keep monopoly fears at bay. Throw in some feigned competition in areas of the business while fleecing the public on other items, and keeping the gov happy by focusing on keeping CPI items at low cost to alleviate wages growth. If your cohort companies step out of line, give them a good smacking of market swamping until they bleed down to a level they pull back and cooperate or go broke and another sucker steps in.