That's a great point: I would much rather buy 5% amphetamine 95% sugar from a licensed seller than whatever the hell I'm getting on the street. While contamination with rat poison is mostly a myth contamination can produce nasty results.
It's more than that though. Not just licensing, but motive to self-regulate.
You don't buy "(Cartel X) branded (drug of choice)", so there is no reputation to protect by it; if one batch is bad, meh, no big deal.
Whereas if it's available at a drugstore...CVS and Walgreens compete, and have reputations to maintain. Any contamination not only would have federal implications, but also would have direct economic ones, such that they are incentivized to self-police. To ensure their entire supply line is coming from reputable sources, is randomly tested for contaminants, and anything that slips through leads to a recall. Otherwise, they face a loss of business to the competitor.
You don't buy "(Cartel X) branded (drug of choice)", so there is no reputation to protect by it; if one batch is bad, meh, no big deal.
Whereas if it's available at a drugstore...CVS and Walgreens compete, and have reputations to maintain. Any contamination not only would have federal implications, but also would have direct economic ones, such that they are incentivized to self-police. To ensure their entire supply line is coming from reputable sources, is randomly tested for contaminants, and anything that slips through leads to a recall. Otherwise, they face a loss of business to the competitor.