[mcdeltat]

Out in the bush, where the distances are truly stupid (like 200km to the next anything) the care for and policing of the speeding limit is much less, if present at all. The speed limit there probably won't affect traffic fatalities that much, as the density of vehicles is very low. So surely the speed limit may as well be higher.

[Symbiote]

Out in the bush the risk is hitting animals, and the roads are narrow.

The speed limit is already 130km/h in Northern Territory anyway.