“ It’s currently “easier” to access from the black market than the legal route these days,”
It’s easier to get some laced with fentanyl too.
Honestly, I'm sure it could happen, but what would be the point of lacing Marijuana with fentanyl? All you're going to do is piss off a customer or perhaps kill that customer, and that's not exactly a winning formula for a “dealer”. You certainly aren't going to “hook” someone on Marijuana by doing the retarded thing you're suggesting, although I have little doubt there are morons out there who subscribe to your lunacy and have attempted that stupidity. Certainly nothing I've ever run across or heard of in my associations with those who purchase off the Black Market.
Millions of Americans are still purchasing weed on the Black Market. That's a fact, and the primary reason is Excise Taxes.