Legal pot in trouble in California

The Washington Post explains that the legal marijuana business was struggling in California already, and the COVID-19 situation is making it worse. 

I'm not sure what State in the US is considered to have got this right, because as this report notes, State regulations and taxes on the business mean that the black market doesn't just disappear:

With the drug legalized, underground dealers felt emboldened to expand their operations, setting up expansive delivery networks, undercutting the prices of legal pot and depriving the state of marijuana revenue. California initially expected about $1 billion in new tax revenue in 2018. It took in $342 million. Untaxed and unpoliced, black-market pot is estimated to be much larger than the legal trade in California.