Here in WA, MMJ is subject to sales tax.
I tend to favor collectives (kinda like a dispensary) that actually do collect/remit the sales tax. If they are doing their best to comply with the law, I figure I'm less likely to get caught in a raid (I have a co-worker who has been caught in a couple of raids on collectives), and I consider them to be more honest people.
Now, SHOULD mmj be taxed? I don't think so, but I'm waiting for so many things in life to be "fixed", and this is just one more item. When the Feds finally figure out that MMJ isn't a drug war problem, but is instead something that benefits the life of so many people with harsh challenges in their lives, and get it moved over to the "approved" list, then we'll see the end of taxing it. Until then, I'm just glad I can obtain my meds legally.