Where there is a will, there is a way. Black markets foster because desire for illegalized goods does not simply recede because those goods are banned.

It seems the bigger issue is the illicit drug market and much of the violence is being fueled by gang turf wars. I wonder if decriminilizing all drugs would help decrease violence and drug-related deaths like it has in Portugal? https://mobile.nytimes.com/2017/09/22/opinion/sunday/portugal-drug-decriminalization.html