False equivalencies. It's easy to buy quality unadulterated pot and booze for people on a wide variety of budgets -- not so heroin, which is exceedingly expensive on the street and of increasingly suspect quality besides. Also, per results from Switzerland, it's already cheaper to provide subsidized medical heroin in cases of refractory addiction than it is to pay for the costs related to a user's continued dependence on street drugs -- i.e., first responders, acute care, hospitalization, property crime, etc.