What if they only think they live down under?
Well, I think I live in Australia.
When I fly NW (roughly) I seem to end up in Brunei.
When I fly WNW (roughly) I seem to end up in Dubai.
When I fly ESE (roughly) I seem to end up in New Zealand.
From Melbourne sailing south I end up in a place the locals call Tasmania - mind you they think I just live on that big north island of Tasmania.
The northern tip of Cape York looks the right shape.
The very western bit (Steep Point) seems in the right place and travelling as far SW as possible I land on a corner with blustery winds and a lighthouse - probably Cape Leeuwin - it sure don't look like California!
The sun seems to do what I expect for Australia -
rises in the SE and
sets in the SW (in mid-summer).
At night the Southern Cross (I guess - it looks like the one in the books!) rotates about a point roughly 30° above the horizon!
That's enough for me yes, I think I live in Australia and it is in about the right place.