well just cause one or several aussies say it, don't mean we all do, most of australia concerning language in media and stuff is overrated. How do I know? I'm australian and not me, nor my parents or any of my friends use the kind of language that americans think we do, course we say g'day from time to time and 'mate' course we do since we're too friggen lazy to say their name or 'friend' XD
Throw a shrimp on the barbie? Ugh you americans watch too many movies, no decent Australian in their right mind would say that nor the other kinds of phrases that we are so-called famous for. We speak regular english with the occasional language shortcut and maybe swear more than most others since it's considered normal in Australia (Carl Barron ftw).
this
and i only ever say mate to someone over 40 considering it's a dying trait