If you drive any distance through rural Oz, they pop up all over the place -- as do Six Mile creeks, Seven Mile Creeks and Nine Mile Creeks.
If the early settlers didn't borrow aboriginal place names or import their proper nouns from England, they just went with the most obvious. Thus Oz boasts the Great Sandy Desert, Great Australian Bight etc. In fact, your wife's home state is a perfect example. In the U.S., they managed to come up with 50 original names. In Oz, they settled for, er, South Australia and West Australia. When the Northern territory gets statehood, they'll no doubt call it North Australia (although Capricornia would be a better choice).
Tell your missus they also serve Coopers at the Eight Mile Creek restaurant.