Just to expand and conclude: if aggressive policing works to stem the drug flow by choking the demand, then such tactics should be used for "coke snorting yuppies" as well as "poor crack addicts." That it isn't suggests that there's another impetus (or, an impetus for not using them on the former). The tactics used in enforcing drug laws are often harsh, if not cruel. In the past, the line between American institutions meting out harsh or soft punishments for transgressions has been the same as the one between white and black. So I'm perfectly comfortable saying that race makes all the difference in this context.