This blows my mind. We are paid for our time and in return, we carry out the tasks required of those paying us for that time. It is a clear agreement with clear benefits (theoretically) for both parties. I get X hours of pay and they get X hours of whatever task they need accomplished.
So why the fuck would we change ANYTHING about our lives outside of those agreed upon hours? Why would we allow an employer to police ANYTHING about our lives? It blows my mind.
You don't need a drug test to tell if someone is on drugs at work – whether that be alcohol, weed, meth, or anything else. You need common sense. And if you can't tell if someone is on drugs, then they are obviously accomplishing the agreed upon tasks in the agreed upon manner for the agreed upon time. What's in their veins is no concern to you in that case.
But drug tests go beyond that – they are a mechanism for policing our behavior outside of the workplace. For example, THC stays in your system for relatively 30 days. So that drug test has nothing to do with me being high at work – it is to enforce how they want me to live my life outside of work. They want to break the fundamental agreement of employer-employee relationships (the exchange of time for money) and control you outside of that set agreement by making you give them you bodily fluids to inspect!!!
Why anyone is willing to take a drug test, whether they are clean or not, is beyond me.