No shit. And I say that as someone who hasn't indulged in weed in over 25 years.
Prohibition is only good for bad guys and private prison operators.
As far as companies that drug test--take your minority report thinking and cram it up your corporate ass. If you are a private citizen who thinks it's a great idea, cram it up your private ass. If you are worried about people coming in high and doing a poor job--maybe you can wait for that to actually fucking happen before preemptively sticking your nose into people's private lives and penalizing them for something they do on their own time.
I'd have to be truly desperate to take a job with a company that drug tested despite knowing I'd pass any test given any time. I'm still employed and have done some semi-serious job hunting, and those that test are not even considered. It's a sign of a culture that I know I wouldn't get along with.
If your whole concern is "things that are detrimental to society", I suggest you start pushing for banning unmoderated social media (Facebook etc). I consider that shit far, far worse than any drug.