It's unworkable without banks
Good intentions and honesty are not common in the dope trade. All the folks who get a license to work with marijuana are going to follow the rules, for a few years. They will observe how the state runs the activity. Soon they'll stumble onto the loopholes. Then the rip-offs shall begin.
Why are people submitting applications to grow and sell pot? Federal agencies are not going to allow dope money in any banks. Good luck lugging around a box of cash. You can't get a checking account for a weed business.