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.

No sane person uses Bitcoin as a currency because it is a fundamentally unsound ponzi scheme for suckers. I don't want my salary to be subject to the vagaries and manipulations of the Bitcoin exchange rate.

If you don't want to hold Bitcoin or be exposed to price changes, you can set your hourly rate in dollars, be paid at the current exchange rate and immediately convert it back into dollars. The advantage of this over being paid in physical cash is that it's electronic and then you're not carrying two weeks salary in physical cash on your person for somebody to mug you.