Violence levels track inter-firm cartel stability, not market structure

Evidence

The real reasons for the extensive use of violence by the mafia may depend not so much on the structural features of the marker as on contingent factors. One such factor involves the various relationships among mafia families. The more stable and organized these are, the less the likelihood of violence. For instance, evidence suggests that American mafiosi resort considerably less often to violence than their Sicilian counterparts, both within their world and without. In the United States there has not been an all-out mafia war since the 1930s—the so-called Castellamarese war—while in the same period two such conflicts have occurred in Sicily, with hundreds of killings. — Diego Gambetta, The Sicilian Mafia The Business of…, 108