In the first one, Sonny’s role is central. When he flies off the handle and starts over-reacting after Don Vito is hospitalized, and when his sister is roughed up, you know that this is not wise, but you don’t know exactly HOW it isn’t wise. The answer is, when you are a hothead, you aren’t careful, and you are easily setup. They KNEW that if they could get sis to call him, that he would drive out immediately and have to go through the toll booth.
Click. whir.