I don't know where you get this, maybe start-up land. I have been a dev since the early '90's and all kinds of enterprises do drug testing. Most utilities, health-related organizations, defense contractors, transportation businesses and even many large manufacturers routinely drug test potential employees. Most only test for pre-employment screening, but random testing is still used in many places.

Most recently, three years ago, I was tested for a contracting gig at a Wisconsin power company for a web dev job.

Sometimes I think startup land is a different planet, around here pretty much every company who would hire a software developer drug tests AND background checks unless maybe it's a really, really small company. Some even do the hair drug test instead of the piss test.

I've ALWAYS been drug tested before starting a software job. I've been drug tested working for the most benign of industries. I actually had a friend who quit weed so she could get a better paying job.

That sounds like a different planet to me. I don't know of any big tech company, let alone startups, that drug test. I wouldn't be surprised if this was the case for dev jobs in older industries but it doesn't seem to be the norm any more.

modern tech cos do not drug test

There is still some risk. I think you're forgetting that (1) illegal drugs are hard to obtainn--no walking into CVS--and (2) illegal drugs are not reliably sourced--I trust mass manufactured marijuana far more than I do from the sketchy guy on the corner.

That's not necessarily true, especially in consulting firms. I am drug tested somewhat regularly.

"If you work in tech"

You think there are no tech jobs in consulting firms?

What is tech? If you mean sv startups perhaps. But pretty much any embedded sw shop will at least test at hire on.

google, amazon, fb, netflix, apple...these are not "startups"