A few nights ago I watched Marked woman (1937), which I think illustrates more than many better-known Mafia movies the mechanisms of organized crime and why it flourishes and persists. It is based on the arrest and trial of Lucky Luciano, a Sicilian-born New York mafioso who was instrumental in establishing Cosa Nostra in America.
Significantly, I was watching the rather obscure film just as a major round-up was made on the New York mob. Which was seen (and is) a major accomplishment. But also indicates that organized crime is still very much with us.
The stubborn survival and pervasive influence of organized crime can only be traced to omerta', often incorrectly (or rather, incompletely) defined as the Mafia's code of silence. It goes without saying that if you're a criminal you're going to be quiet- you're doing something illegal. The omerta' that keeps crime and other forms of evil going is the silence of others, as stirringly presented by a young and handsome Bogie in his closing argument. He refers to a "supine and cowardly city" that expresses outrage at corruption but will do nothing to fight it. Placing the burden on the shoulders of the few witnesses who will come forward- in this case, an unlikely group of night club prostitutes, headed by Bette Davis.
Highly recommended. Watch out for the subtle but menacing performance of Eduardo Ciannelli as the villainous Vanning, and his psychologically convincing explanation that his real motive all along was not money but power- "I like to tell people what to do."