there's no evidence but I believe the political class is protecting the larger drug rackets because they get paid by the larger drug rackets - i.e. a skim or cut of the action.
For example Mayor Marty Walsh in Boston has been part of the Irish clans (mafia) his whole life and weed is basically still illegal in Boston - 2 1/2 years after legalization, no retail stores. 62% of the city voted in favor. How can you ignore the fact that the Irish mafia has run drugs, gambling and sex in Boston for decades? need I mention Whitey Bulger, who's brother ran the State Legislature.
The changes the state Legislature made to the law, and the security/regulatory requirements imposed by their appointees, could not have been written better to preserve and prolong the black market. Coincidence? There are no coincidences in politics.