there is a big problem still with all the states that have legalized pot
they used restricted growing and heavy taxing as part of the reasoning to legalize it
the problem is, this is not like trying to distill ethanol in your garage without poisoning yourself
anyone, anywhere in the US could grow all the pot they need for their own use, in their own garden or makeshift green house, literally for free.
The price would go near zero. There would no black market. And there would be no tax 'benefit' to rationalize it.
That is where it will all end up eventually - as long as legal outlets are charging $400 per ounce for something that literally grows like a weed, there will still be a black market.
Sooner or later someone will sue the government, and argue that if its legal, then its LEGAL, and you cannot stop people from growing flowers, tomatoes and pot for their own use.