The elephant in the room is the current roadside test system.
I have no problem with peeps doing drugs, but is pretty much impossible to get away with where I live.
I have been tested twice, 'random roadside' by unmarked cars and proved clean.
But others have not been so fortunate. A mate who had smoked weed the night before, was sober, but still came up positive and lost his license.
Another dude, was pulled up out front of my shed and first tested + for meth, but then the 2nd test which the officer offered came up negative, and was let go.
Seems the tests are unreliable and don't test for you being under the influence at the time, but if you have had any in the last few days.
A mate who is a lawyer has 40, yes 40, cases coming up in the local court!
At least with BAC there is a 0.05 limit