I was talking to the HR Director of a very large company the other day and a subject somewhat on this line came up during our lunch. I made a comment about all the unemployed and underemployed people in our area. He said that he wasn't going to get in a discussion about how some unemployed didn't want to work because they could negatively affect their government assistance, but he did say that one of the biggest reasons there were so many unemployed younger people was that they couldn't pass a drug test. When I asked how pervasive that problem was, he told me that his company and two other large companies in the area had recently started requiring the temp agencies to drug test all the people they sent to them and immediately started running short on temporary workers. Then several of the temps that passed the test and were sent to them were a little shady on their legal work status, which made the problem even worse.
When I was still in the service, it seemed that we always had about a 10-17% failure rate on drug tests, not it appears that it's much worse.