Australia has an average "top speed" of 100km/h (110km/h in certain states) - whereas many other countries, with varying degrees of better or worse infrastructure, have average "top speed" of 130km/h - and yet have similar traffic fatalities.
Turkey: 130km/h (and fairly poor infrastructure compared to europe): 6.7 fatalities per 100k France: 130km/h (most people drive at ~145 on highways - only 1 point if you hit a radar) - 5 fatalities per 100k Australia: 100km/h - 4.5 fatalities per 100k
It can't just be speed, otherwise other 'similar' countries would be orders of magnitude above Australia.