Politicians should be few we removed from infrastructure decisions and the staff numbers in vicroads halved.
People a few practicalities
As they (Pollies) control the cash flow, the above is unlikely to happen.
Sydney will always be the main airport and if a 2nd one is built, Sydney combined will always be the main arrival city for international.
The freeway will also always be the main mode of transport to the airport carrying at least 20mpa with or without rail. Even if you had a railway and the freeway became blocked, will rail suddenly be able to handle a 5 fold increase in ridership? And you don't build a rail line for a 1 in 10 year event.
Sydney and Brisbane only got airport lines due to private investment, both went broke in some form due to slow take up. 15 years on business is very much improved, but still continue to be many times above standard ticket prices. Full Private investment for a Melbourne Airport line requires ticket prices to be around $25-30 one way.
Are Victorians willing to pay? Probably not.
At the last election the people choose a party without an airport railway on the agenda, the people have spoken!
As I said before, Adelaide will have a rail connection (LR) to the airport before Melbourne.