Crowded criminal markets make informal protection economies organizable. [causal]
Why is it that this improbable sector is susceptible to organization? Partly because of the general efficiency of protection in Palermo, and partly because, since there are so many perpetrators (not least because there are so many protectors), it is not in fact out of the question that two might in fact try to snatch the same bag. In any district in the city center one can find at least ten of these characters at work. In addition, the need for a reliable fence and shelter from both police and other criminals ties muggers to a particular area, and this makes them controllable.
XREF: Relates to how dense competitive markets generally invite coordination and informal governance — parallels economic theories of cartels and state formation.
Diego Gambetta, The Sicilian Mafia The Busi…, loc. 614