I didn't realize you were in Oz mate. I have been a farmer for years in Australia and I also lived a lot around the EU... I watched that unification process first hand. Yes, you definitely need to show your passport when you are leaving the Australia.

Things are even more hardcore in places like Bali where you need to show your passport to even get into the check-in zone. They are worried about bombs.

I was recently on a flight that stopped but only transited in Australia. We never left the airport or went through immigration or customs. However they tried to make me go through the body scanner - which I stoutly refused. However on the same route back up to Asia a young Indian man was not allowed to board the plane because he did not have a "transit visa" for Australia. He was never going to leave the airport, go through immigration or customs. He was only going to switch planes within the airport but needed a visa for that! Outrageous.

The poor guy was only young and going home to India for his sister's wedding. I waved goodby to him at immigration. I'm sure he sorted it somehow.