"People are still being arrested for growing it, possessing it, and selling it; it's not truly legal; people are still being raided and having their lives ruined; and sales that are taxed are funding the abduction, extortion, and or imprisonment of innocent people."
The cannabis plant should have never been made illegal; it was unconstitutional to begin with and has done far more harm than good. "Out of the 8.2 million marijuana arrests between 2001 and 2010, 88% were for simply having marijuana."(1) So in nine years' time, 8.2 million people were abducted, extorted, and or imprisoned for victimless actions related to a harmless plant with an LD50 level significantly less than nicotine. That's over 7 million victims of domestic terrorism within a 9 year period. The dose that is considered to have a 50% chance of killing you (LD50) for nicotine is a mere 0.5-1mg/kg of body weight (0.1mg/kg for children). The LD50 for THC is 1,200mg/kg of body weight. That means that nicotine is 119,900% more toxic than THC, and yet the government has spent copious amounts of extortion proceedings (tax money) funding order-following mercenaries (cops) to abduct, extort, and or imprison people over THC. The only reason states are making it somewhat legal is because it brings in more money; it's more profitable to extort licensed growers and retailers while simultaneously still benefiting from extorting the innocent people who have "too much", or who are selling it without the nanny-state's permission. People are still being arrested for growing it, possessing it, and selling it; it's not truly legal; people are still being raided and having their lives ruined; and sales that are taxed are funding the abduction, extortion, and or imprisonment of innocent people. Stop contributing to a terrorist organization who is still throwing people in cages over flowers, and would have thrown you in a cage for possessing a small amount of the plant matter (even a roach) just a decade or two ago. Giving more money to the same terrorist organization who have caged, extorted, and killed countless people over marijuana, by buying taxed marijuana, makes as much sense as demanding the largest perpetrator of gun violence to regulate gun violence; but here we are, year 2018; heading straight towards idiocracy in 2019. The regulatory capture related to cannabis is creating victims and funding victimization, not creating and funding freedom. No human should be thrown in a cage for growing too many plants, or for engaging in too many consensual transactions. The government has acknowledged that cannabis has therapeutic properties, and they even have patents for cannabinoid-based medicines. So basically it's a crime to sell people non-toxic medicine without permission from the state, and even if you have permission, you can still sell "too much" and be subject to punishment. Evidently it's illegal to provide too much value to your community; you're only allowed to engage in the amount of voluntary transactions that your permission slip permits.
"The black-market supplier funds significantly less terrorism."
The presence of a black-market is a lagging indicator of the degree of regulatory capture and societal oppression present. A black-market does not involve any actual crime or violence, only voluntary transactions deemed illegal by an imperious central authority. A black-market is a byproduct of state coercion and a regulated market. If market activity involves coercion and or an absence of consent, then it doesn’t qualify as black-market activity, but instead, red or pink market activity. The largest perpetrators of red and pink market activity (coercion/extortion/war) are governments. So what's the difference between a black-market supplier of cannabis and a retailer and or a licensed caregiver? The black-market supplier funds significantly less terrorism. Stop funding oppression! Vote with your dollars! Find local suppliers who do not enthusiastically submit a portion of the effects of their labor to the same organization who is extorting people and punishing them over victimless actions. If you knew that giving somebody money for cannabis indirectly funded punishing people for victimless actions involving cannabis, then would you give that person money? Stop giving your money to a coercive mafia trying to micro-manage your life and the life of your neighbors.
"Tax proceedings fund, and thus perpetuate, the practice of widespread extortion."
If purity and third party testing is what you are concerned about, then negotiate with your supplier to provide lab test results, or pay for the testing yourself. Most cannabis growers want to be providing pure, potent, and safe products to consumers, as it's never a good business model to sell harmful products marketed as healthy or healing. You could start a testing company yourself, or even help organize crowd-funding for testing products from local black-market suppliers. Tax proceedings fund, and thus perpetuate, the practice of widespread extortion. Do you really want to walk into one of these cannabis stores and hand money over that you know a portion of will go towards funding the practice of widespread extortion and punishment for victimless actions?