In the open, and at dusk or at night, one runs the serious risk of hitting a kangaroo. Cars are older than in the U.S. with the average age over 10 years. High initial cost and a climate that does not promote rust helps. With cars and everything else, they tend to fix, rather than replace. Most Aussies know which years of each car to avoid and what the faults are of each make, model, and year.
Older cars are actually more prone to theft than newer ones, as parts demands increases.
The car factories are now installing as standard equipment alarm systems and heavy duty locks to counter the high auto theft rate. Driving in the outback has its own risks. You can get to most places without a 4x4, as long as you don't mind a dirt road and don't go in the north during the rainy season. Fuel is often unavailable late at night. Australian drivers are reasonably skilled, though timid.