I have never had a drug test, and that includes several jobs working for defense contractors. (The law said they had to have a plan for testing anyone they suspected of drug use. It didn't say they had to suspect anyone.)
I've never had security clearance of any kind. Highlights that all required drug testing were: restaurant national headquarters, towing/insurance national headquarters, theme park, defense contractor for non-secure projects, and a bank.
Though now that I think about it I have technically worked at two companies that didn't drug test: my own, and a small 3-man startup I did some work for.
It's worth mentioning that I live in a red state. I suspect blue states have cultures that are a little more lax on drug testing, though I have no real data to back that up.
Here's the sectors I've worked in throughout my career: Insurance, banking, marketing, entertainment (theme park), restaurants, and defense. Every single one of my jobs in those sectors required drug tests prior to employment.
