Yeah Australia is slightly different to the US in that it's huge but there are very few people living here. Take the largest state: Western Australia which is literally 4 times the size of Texas. But do people drive from Adelaide (capital of South Australia) to Perth (capital of Western Australia)? No, not generally. It takes 28 hours of non-stop driving. And the thing is, there is hardly anything in between. This means you have to be careful about fuel stops and maybe even have a satellite phone. Look up the Nullarbor Plain of you're interested.

People "from the country" might drive several hours to visit relatives and you might drive 3-4 hours to go to a camping/holiday destination, but if you're headed to another major city, you are most likely going to fly.

The closest other capital city to Adelaide is Melbourne but that's still ~8 hours away by car. But there is a really nice scenic route called the Great Ocean Road which you would usually do over a a few days.