A giant island that's also a continent? Come on. That's a little farfetched, isn't it? Poisonous ducks who are also mammals? Hobbits and wizards?
Some copyright pirate "goes away to New Zealand" or somewhere, never seen again? I see what's going on there. Ditto with prisoners long ago. "Uh, sure... They're not here... because they were all sent to... Australia, yeah...."
They didn't even invest much thought in the name. Just pick a country off to the side and change the ending a bit. Could have been Germania or Turkeyland.
A quick Google search will reveal the truth. "Australia doesn't exist" gives lots of hits. I didn't actually look at them, but there are a lot of hits.
I haven't seen Australia so it must not exist. Kangaroos are probably some weird genetic experiment. Imagine the effort put in for that though just to get people to believe a continent exists.
And then they needed to get a bunch of people to say they're from there and insist it exists. There must be some kind of payment scheme.... Health care, free college... Making more sense now, right? I bet they're international students frequently too. It's hard to go to college at a place that doesn't exist.
There's plenty of open spaces on the map in the southern hemisphere.... *Bob considers making a Bobland continent.* Imagine the coordination that must have happened long ago for everyone to buy into this Austria-land idea.