I absolutely agree with you! There has been no proven compelling reason for across the board drug testing, no cost savings, no better productivity, nothing. It is just a phallacy that the drug testing labs continue to propagate across our society.
Not to mention that there is no test to find out about current use of marijuana. The THC stays in your blood (fat cells I think) for up to a month so what are they testing for? That you ran into a college buddy and managed to score a joint and then smoked it a month ago? Come on!
On the other side of the coin, I've needed a job and went through drug testing 3 times. I have not used heavy drugs for many, many years, but used to be a regular pot smoker and I managed to pass all 3 of them. Also, I know that the residue from drugs such as cocaine, heroin and meth only stay in your system a few days, so if you fail because you are snorting on the way to your test, the the test has worked, because it proves you are stupid!
And finally, I have always been an outstanding employee that rarely, if ever, calls in sick, works twice as hard as others and I am professional in every way I represent my employer. Kinda blows the theory that drug users cost the company money, doesn't it?