An excellent question!
People from the northern hemisphere tend to forget just how big Australia is until they get here, and start travelling around our capital cities. It doesn't just take a long time because they're clumsily designed - it takes time because this place is big. Our island continent is as large as the USA turned upside-down, then stretched a little bit.
People think Sydney is the half-way mark of the east coast. Nope. Cairns is as far from Brisbane as Brisbane is from Melbourne. And there's still a fair bit more country to explore north of Cairns!
Count on a 2-hr flight (3 if it's summer time), or 2 days to drive.