Addiction and abuse rates would skyrocket, though. With an availability similar to alcohol, that would begin a plague that would envelop the country with astonishing speed. The problem with those drugs now is already a big problem, but if you put them within reach of every single adult you could bring a country to its knees.
Yes, legalizing them would be a boon for commercial interests, but that is practically the only people who would benefit from this. Oh, and drug treatment industries! They'd become as ubiquitous as mental health businesses. Big Constipation would replace Big Tobacco.
> prevent deaths from adulterated drugs.
The influx of death and destruction introduced by that legalization would make adulterated drug deaths look quaint.
Whatever the solution to this problem is, it won't be full-scale legalization. These drugs that are almost impossible to use responsibly, and are guaranteed to be highly addictive.