Before I retired I worked for a "fortune 500" style company...electronics in satellites, cell phone, auto ignitio amd engine controls. I worked in the automotive division, non-union and we had random drug testing. Yes, some were caught in the net and quietly left..
Our plant was about 30 miles from my house, off toward the city, so we had rural, suburban and urban employees. It seems the urbanites were the more frequent failures.
We had one lady..heavy, near retirement and very nice, who failed the test! We were all shockedand asked each other.."not Pat"?? Well, when the investigation came through, it seems Pat was a habitual eater of poppy seed rolls..
One time when my number came up and I went to take the test (right in the facility) and being a dept head, I was missed. When I returned, upon being asked where I had been, I replied that I had to "go pee in a bottle for my brother". Admittedly, a couple immediately asked how I managed to arrange where I could fill the bottle for my brother.
Their mistake; they assumed I had a brother who worked in the same plant and for the same company...Fact is, my brother was the technician who worked with the firm who was doing the testing..so I filled the bottle for him to test..