Planning with no Alternate at all is simply NOT an option.
Actually every airline is bound by local law for the country into which they fly. Australia's fuel rules are written to not plan an alternate in most operations.
Just as Qantas must plan an alternate when flying to a European destination, in order to comply with JAR/EASA, so an airline need not plan an alternate flying into an Australian port when the weather is above the alternate minima. The Operations Manual of the airline needs to reflect this, of course - just as an international airline's Operations Manual needs to reflect the local laws for each country into which it operates.