OK, there used to be a large population of Dropbears here, and they instinctively knew not to eat Australians. For example, seeing somebody eating a 4'nTwenty Pie, or putting a shrimp on the Barbie, or wearing a hat with corks hanging down from it, or picking your nose = they really knew not to touch these people, and only went for the foreign Tourists.
(For foreign tourists, showering in Wombat urine was said to reduce the chance of attack, and reduce the chance of doing anything much at all)
Unfortunately (for the Dropbears) they became close to extinct when the Yowies discovered how delicious they were, and killed of 96.2% of the population. The remaining Dropbears live in isolation and tiny groups, feeding mainly off backpackers.
Norm