@Steve *******
you obviously don't know that DTA can be complex and not always ine country gets everything.
They can agree to share, depending on type of income and also declare types of income taxable for both, then most times making the tax paid in one country deductable in the other, but your DTA might be very simple, but there are a lot more countries than Australia.
How do you live in Thailand for 25 years without a permanent home?