Cost benefit is an integral part of risk management. To put it in ridiculous terms an empty sky is a safe sky so why don't we keep our aircraft on the ground?
I am not sure who was writing Warren Truss's copy for him but safety has never been an absolute and has never been pursued "regardless of cost".
Nowadays safety management systems (SMS) try to predict what might happen and mitigate against it instead of waiting for an accident. However even an SMS has at its foundation a concept of what the populace will accept as a risk in order to enjoy the benefit arising from the activity. We call them Class A for unacceptable, Class B for skydivers/SAS troops, Class C for higher risk but manageable and Class D for acceptable. The SMS endeavour is to be forever trying to mitigate the As to Bs, the Bs to Cs and so on, however at the end of every mitigation event there comes, conciously or not, a cost benefit study.
A modern day example is driving. We accept the accident rate in order to be able to use vehicles. Technology exists to reduce the risk of injury or death in an accident. When it is developed it is expensive so most of us are forced to continue to carry the risk of driving, that is our own personal cost/benefit study. As the price of the technology comes down many of us eventually can afford it so we do. Cost/Benefit hard at work and the airline industry although many levels ahead of the automotive, is governed by the same rules of human behaviour.