Commuters have been subject tax in Aus for decades, nothing there has changed. If your family and life outside work are in Aus, you are resident for tax purposes.
You do, however, only pay the difference between what you pay in the country where you work and what you would pay earning in Aus. The Korean dael is, I believe, net of Korean tax, so the amount you pay is substantially less than if you were paying full Aussie tax.
Americans have to pay tax even if they AREN'T resident, so I'm not sure what you mean there.