I have not spent much time with this book. I have mentioned copy-cat crimes so often in my analysis of how tempting it can be to join in social behavior that I was not surprised to find copy-cat crimes listed in the index as a topic that applied to movies. In agreement with where I found it in this book, I quote:
Which brings us to Taxi Driver (1976), the ultimate vigilante picture -- an intentionally ironic fable . . . (p. 167).
That is in Chapter 6, The Violent Arts: Pop Goes the Culture. Chapter 5, Counter-Counterculture: . . . is food for thought if you want to become more like me.