Retail marijuana products, from grass to edibles, are clearly marked as to its concentrations. The price point also is a reliable indicator as to the potency of a particular strain. You can buy a pre-rolled joint for $5 or as much as $30.
People don’t buy weed from strangers in the park anymore. You know what you are getting. I suppose inexperienced users would be more likely to overdose.
I have no idea where you are from. All up and down the West Coast the amount of marijuana consumed from illegal sources is greater than the amount consumed from legal sources... Why? Because it is cheaper and the drug pushers add other illicit substances to “enhance” the users experiences. A lot of people have died smoking or eating marijuana which was laced with fentanyl.
Overdose deaths are up 800% since 1999 which I think is an indicator that the number of people buying drugs from “strangers in the park” is way up... not down. People who use mind altering drugs especially "experienced users" are on average just plain stupid. And they tend to trust "strangers in the park" whether it is to save a few bucks or to get a more vivid experience.