The primitive is only telling .0000001 of the total story.
Things have changed big time since the 1980's. I tell you the Temp Agency's do drug testing but unless they are off the charts will send out workers that score high on drugs as the Company's need the man power.
Spot checks are done when an accident occurs to the laborers. However the supervisors, company workers are never checked and a Company Officer taking Coke will have no problem.-------
I remember when the first testing for pot came out in the military, What a mess that was, the tests were in the beginning very bad, destroyed the lives of thousands of men. Bad tests sent hundreds of those that did not drink, smoke or do drugs home.