Wonder if Doctors, Nurses, Truckies, Bus Drivers etc etc could claim to achieve such impressive results if given a similar level of testing.
Depending on the individual employer, many of these groups of workers are tested. I was regularly tested in the military (big drug/alcohol problems there) and when I was working for the government railway. The only place I have never been tested is the aviation workplace. I was never tested when I was working as a safety officer and I have not been tested while working as a pilot.
Police are also regularly tested, though many continue for years before they are caught.