It's so much more that that. The vast majority of jobs that are worth a shit drug test, by and large the ones that don't choose not to because they're desperate to exploit people that come to work for them.

Source: pretty much ruined my life sticking to shit blue collar jobs that didn't drug test. Every other professional job wanted to drug test even if it was just to sit at a desk and never even come remotely close to heavy machinery.

I fucking loathe the fact that this is a thing. Jonny Jackass can go home and drink himself stupid, do all sorts of terrible shit, come in with a hangover and be fine. I smoke once 2 weeks ago on MY time and get fired after a drug test.