"Australia is sparsely populated and certainly can use more settlers."
The biggest problem there is that central Australia is mainly desert..... something to do with salt (in the sand.... don't ask me..)... Central Australia is know as, 'the outback'.... and I don't laugh at it sense there are few people that can actually survive there...
Personally, I have many ideas on how to make the central desert areas thrive ( with water and vegetation).... But since the Americas have had about the same time on the global map, and since no one else has come up with an idea that is plausible... I think my ideas probably would not work... :P
Anyway...