there are also concerns about microbial contamination with weed that is improperly grown/processed. this is exactly why weed ought to be legal but regulated. people engaged in grey market sales are performing an end run around the new safety regulations.
but anyways, that's kinda besides the point. if people are growing stuff for their own consumption, I don't really care how safely they do it. I'm all for people distilling whiskey at their own risk. but if you're going to make money selling stuff to other people, it should be as safe as is reasonably possible. somehow I get the idea that random dudes selling flowers/concentrates/cartridges aren't looking that deeply into their supply chain. people died recently from what should be a fairly harmless plant.
And events like that also represents a significant financial loss to the producers, which itself acts as a form of accountability above & beyond regulatory penalties that might apply.
Basically, it doesn't matter if microbial contamination of weed isn't any more dangerous than for vegetables because current agricultural products have a remediation process in place to mitigate the danger, a process that doesn't exist for unregulated weed.
You could also never be caught for moonshining, I know drug dealers who have sold for years without any police contact.
[0] People died from consuming THC carts that were tainted with Vitamin E acetate. Otherwise, weed products have not killed anyone ever.