US drug control agency will move to reclassify marijuana

One major effect of this is that weed stores will be able to use banks and payment processors legally once the regulators catch up.

I don’t get why they don’t just use Bitcoin or Ethereum.

Mainly because your employees, suppliers, and landlord have no desire to be paid in Bitcoin.

What does that matter? You can convert Bitcoin into cash. But then you can do that in an undisclosed location at your leisure instead of keeping a mountain of cash in your publicly advertised storefront location and becoming a huge robbery target.

Also, it doesn't seem like it would be that hard to find someone to accept it as payment, since they can convert it to cash too. And the sort of landlords/suppliers/employees willing to do business with a dispensary seem like exactly the sort who would accept Bitcoin.

All of the legit Bitcoin-to-cash orgs will report that to the IRS, and then you're back to square one: what do you do with that wad of cash? Orgs that don't report to the IRS probably aren't giving you a good exchange rate, and you're still left holding the bag afterward.

If you're going through all that hassle, it's much easier just to be a cash-only business in the first place.