I was a professional driver for over 10 years, and as a part of the federal CDL program, random testing was a part of life. One could fail by eating a couple of poppy seed muffins for breakfast, so that was out of the diet. At any given moment, in almost any place, I could be expected to follow a uniformed officer to the nearest restroom or to follow in the truck to a particular donation site, where I was expected to give an "offering." Just a fact of life. Didn't stop drivers from using either drugs or alcohol, but it was a deterrent knowing that your job was on the line for lack of compliance.
I'm not against the program for welfare checks, school teachers, ALL public officials and workers, etc. Call it an economic stimulus. Hiring all the people to collect and run the tests will put a lot of folks to work, which should displace all those who loose jobs from failure in their personal life habits.