Position Paper on Cannabis Matt - completely concur with everything you have said.
Potentially if the result from the referendum happens to be a 'yes' and legalisation becomes a reality, we may see more non-negative results coming through as people increase social use during the weekend alongside alcohol. On the Monday however, one substance may fail a test as non-negative or 'impaired' and the other pass with Zero micrograms per litre of breath no matter how much fatigue is felt from either. If the frequency of failures increase for the reason of "it must still be leftover from Friday night", it is this I fear happening which may reduce the importance of our testing regimes in their current state.
I understand that Saliva testing could provide the opportunity to balance the field of sensitivity between drugs to potentially measure closer to an "impairment" state, therefore not controlling the lifestyle decisions of those at home, however the standards are still comparatively new and companies are feeling safer continuing with the norm should the process be challenged through courts.