Slippery Pete
Because with such horrifically low detection rates, on an expenditure vs. improved safety outcome basis, the money could be much better spent in other areas of aviation.
In the last few years, how many incidents/accidents worldwide can be attributed to drunk pilots? None I'm aware of.
That sounds like the programs encacted to prevent people from showing up to work under the influence are for the most part having the desired effect. Why mess with success?
In the same period, I can think of at least four separate incidents where pilots with unstable mental health have caused a serious incident or accident.
On those numbers alone, it means that surely this money would be better spent by CASA investing in the mental health of pilots - ie 1x free psych appointment per year to talk about your career, life at home, job security stresses, family or marriage problems etc. etc.
Isn't CASA a regulatory agency? Are you really willing to go into a "soft science" doctor to let them evaluate your mental health yearly to determine whether or not you're fit to fly?
It's not rocket science - spend the money where it will have the GREATEST positive impact on safety.
How would 1 psych test per year do that? You're idea suggests that pilots need ongoing professional mental therapy to function.