150kmph won't win to many races on a racetrack, and is well within the safe capabilities of a Mz3 SP23 on many of Australia's motorways, provided the rules of seperation with other traffic are adhered to.
The speed limits are in place for reasons other than safety, they are continually revised and toughened due to a minority of the population controlling the legislation and being heavily lobbied by narrow minded pressure groups.
Speed and traffic camera's not rating highly at elections as both of Australia's main parties are more than happy to collect the windfall of revenue through nonsense fines so neither talk about it.
Focusig on unlicensed drivers or those not knowing the road rules correctly when entering intersections, keeping left whenever possible, etc, should be the priority but its not a priority for the goverment as it increases their costs rather than adding revenue. It requires cops policing the streets and issuing tickets the costly old fashioned way. Its far better for the government to have a camera automatically, 24 hours a day generating revenue without even the requirement for human intervention and the only evidence given to the defendant being a 5 cent letter claiming a piece of photographic hardware and rubber inlaid roading adjudged you to be unsafe at xyz speed.
Rating all cars as equally unsafe to yourself and other motorists at the exact same speed, time of day, weather conditions, etc eg. 100kmph is a nonsense.