Most accounts of mafia protection are biased by the way they become known to us, for we usually hear only about those occasions when something goes wrong and blood is spilled. When things go well, there is either nothing to reveal or no reason to reveal it. The picture we get of protection, then, reflects only interventions after the event, after a dispute has arisen or a crime has occurred. But protection is not simply a repressive measure. On the contrary, as we know, its predominant role is one of deterrence.

XREF: Relates to selection bias and the visibility of successes versus failures — same dynamic as survivorship bias in business and scientific literature.

Diego Gambetta, The Sicilian Mafia The Busi…, loc. 411