This is 100% not true. Perhaps you're thinking of the US system?
Australians pay tax to the ATO if you are an Australian tax resident on worldwide income. Ie, as long as you are an Australian tax resident, you will pay tax on any of your income, derived from anywhere.
However, if you STOP being an Australian tax resident, you no longer have to submit a return with the ATO.
However, stopping being an Australian tax resident is hard. You can't just simply leave Australia and think you aren't a tax resident. You need to tell the ATO you have left and you need to be able to prove you aren't a tax resident, i.e.:
- you've established residence somewhere else, perhaps by taking a longterm lease
- you dont have property in Aus, ie house, car
- you show no signs that you plan to return to Australia
There is a series of tests that you need to pass to prove you aren't a tax resident anymore.
In most cases, digital nomads won't be able to pass the test unfortunately.