Originally Posted by GarryP

It's fundamentally a protectionist measure that they are finally moving towards phasing out. You can buy duty free in Australian duty free, and get through customs. However you can't bring in over 100ml - eg duty free from elsewhere; and you can't transit with it either.

It's nothing to do with security and everything to do with earning money for the airports.

Originally Posted by bcworld

Not strictly true. You can buy at airports which will agree to pander to Australia's rules and deliver purchased duty free to the gate. But yes, Australia is one of very few countries which mandate secondary screening...pretty ridiculous.