The point is actually clownish - drug companies actively apply to get listed on the government scheme for sales here, not the other way around. Why do you think they do that? They spend money to apply for their drugs to be sold in Australia because it loses money???
How are drugs priced in Australia? Honest question, I have no idea.
I'm guessing once a drug is developed, manufacturing is relatively inexpensive.. so selling a drug to other non-USA countries (once the development is paid off), even at low prices can still added profit... I think you said drugs in AUS were about 1/4 the price as the USA.
The question is, how can the company make enough money to pay back the high cost of development in the first place. I get the impression that users in the USA pay most of this, though I am uncertain of this. If, say, the USA slaps price control laws on our drug market, and drops their prices similar to Australia, will that pay for the development of new drugs, or render them unprofitable?