Australian airports are equipped with more sophisticated scanners which can image the type of liquid in that bottle, so the endangerment of the plane is avoided using investment in technology. Other international airports are not similarly equipped and don't identify the type of liquid contents, hence the difference in rules. I've looked into this a fair bit, and it isn't just liquids that the scanners in Oz screen out ... making for much safer travel in Australia compared to USA or Europ, etc. Don't believe it? Try smuggling other contraband such as a jet lighter through a scanner at an Australian airport.