Logo designers refering to Australian companies seem likely to choose several limited criterias…
Making sure people know and recognize the map or the shape of Australia.
clever shape of Australia!
Add to it a terrible combination of colour: Green & Gold!
Refer to the flag of Australia, specifically the Southern Star…
Have an animalia character, usually a kangaroo.
Or a combination of all…
However, the best logos remain the ones that use some creativity and break away from conventional colours…
graphic design history and theory 
Lots of logos I never thought of. Great! Council of the Arts, yeah.