Before there is too much stupidity, if you've never been to Australia, please realise:
1. It's huge. Really huge. I live in one out of two of the closer-together cities in Australia, and they're about 800kms apart. In the other direction, the next major city is 2,500kms away.
2. It's mostly empty (in terms of civilization). Think of driving through rural Utah or Arizona, which are quite similar to the Australian bush.
3. It's mostly flat and full of similar looking landscape.
4. National parks and non-national park areas often look quite similar.
5. There's usually only one or two ways to get around in the country.
6. Mildura is a small town in the middle of bloody nowhere. If I was driving there from here I'd expect to pass through a handful of tiny settlements on the way.
So if you are relying on your GPS to get you somewhere outside a major city, it's actually quite plausible and reasonable that you might not have much idea that you're being led off in the wrong direction until you (don't) get there.
It's also quite plausible that you can die - it has happened before. People get lost, they run out of fuel, they don't have water, the temperature easily gets up into the 40-50C range and - dead.