Of course it wouldn't fool anyone. But a major subtheme of the Trilogy is how people underestimate each other and make fatal mistakes. Carlo thirsted for revenge for Sonny's public beating and humiliation of him. Whatever Tattaglia or Barzini promised him for setting up Sonny was almost irrelevant: here was a chance to get revenge. In that moment he was blind to the consequences of such an obvious move. Ditto Paulie Gatto: he let his greed blind him to the fact that Sonny and Tom had to know that he'd be a prime suspect in setting up Vito for the shooting outside the Genco offices. He, like Carlo, paid the price. As Vito said later: "Women and children can be careless, but not men."

Since Carlo was so obviously behind Sonny's murder, why didn't Vito have him killed? Many of us here believe that Vito couldn't bring himself to kill his daughter's husband. And Vito, confronted with Sonny's death and the urgent need to bring Michael back from Sicily, decided that "this war ends now." It was not a time for more bloodshed. He needed to appear weak and humble, the better to lull his enemies. Besides, he knew Michael would take the revenge on Carlo that he couldn't bring himself to act on.