Estimates may not reflect the ultimate reality.
Why do moonshiners still exist?
Add Arizona and a few other states to that list in the near future...
"But many of Californias 58 counties and 482 cities are also competing to cash in on the recreational marijuana bonanza by tacking on a local sin sales tax of up to 25 percent of purchase price. Cities including Tulare, Coalinga, Del Rey Oaks, and others have stated that they will use local marijuana tax collections to pay for rapidly increasing public pension contributions that are threatening their solvency."
That's 40% so far, and doesn't include the growers, wholesalers, transporters, dispensaries, "each individual's permit to buy the weed" (it exists now), etc.
There will be more and more taxes since the conservatives will not be inclined to act as a check on the liberal's natural propensity to tax. The black market will still be very active.
And they will have to train inspectors, police and prosecutors to enforce all these laws... and jails to build... it's endless.
Taxes will be like socialism unchecked.
They would probably get more from taxing ice cream.
But after while most of the ice cream would be bootleg.