Alcohol and tobbacco dealers aren't involved in shootings in the streets - instead we find them in their shops, carefully following laws and doing business peacefully. Nor are their customers suffering from adulterated goods, or committing robberies to afford black-market prices.
Zetas do not hold up trucks full of tequilla and beer going into the US for extortion because they would be arrested. When your business is legal the solution for dealing with thugs is simple: call the cops or sue them. When you are gray area/illegal your only negotiation is to pay them or pick up a gun creating an all out war.
There are problems with some of the manufacture of cannabis. Criminal gangs use trafficked workers, forcing them to work in cannabis farms.
If I was a criminal gang using slaves to grow cannabis I think I'd market it as some home grown organic low yield crop with images of open fields and nice trees.
Just like eggs from caged hens don't show battery farms, but happy chickens walking in green fields. http://www.ecolovers.co.uk/wordpress/labelling-matters-the-r... etc.
It happens in England.