what is it with Australians and having the cheesiest names for everything? pokies. electricians are sparkies. bikkie. spewie. budgie. brekky. it's like a bunch of babytalk only it's said by literally everyone.
I posit that its due to hardship - not to suggest all Australians are super hard off, but it is certainly true that acronyms/shortened words are more common in rural (think high intensity physical labor) or speed-sensitive contexts (think Wall Street, engineering jargon in a engineering context, such as software, or SMS text-messaging).
Given their origins as a prison labor camp, coupled with a legitimately difficult environment (hot, arid, isolated by thousands of miles of ocean, fairly wild/aggressive wildlife such as crocodiles, snakes, kangaroos), their propensity to shortened, almost mono or duo-syllabic words makes plenty of sense in that context.