The environmental approvals also make it really difficult to get a project of this size underway.
No matter where you plan to put it someone is guaranteed to find an endangered lesser-spotted-puking-frog colony somewhere on the site. Even if the frogs have to be trucked in by disgruntled locals in the middle of the night (not that that's ever been rumoured to have occurred in at least one proposed dam location
) there is bound to be an environmental issue with any site you choose that kyboshes the whole thing. Couple that with noise objections from local NIMBYs and the whole thing just gets Way Too Hard.
While Sydney Airport limps along there's no political point in pushing a new airport, because it's currently a vote loser issue. This means that plenty of people would vote against you for proposing it, but you wouldn't get the same number of people changing their vote to vote for you because they support it. Therefore, it's not an issue that's worth running politically until the existing airport turns into such a debacle that people will support a candidate who offers a solution and will change their vote accordingly.
It really seems a bit stupid having a major Australian airport that has to close early.
I don't disagree, but Heathrow has a curfew. I assume a number of other major airports do as well?