The "Death Wish" series may be interesting historically (for how the early 1970's viewed social issues, and to movie "cult" fans, but they were strictly "exploitation" movies, made (at least the first 3) by a production company that made only that type of movies. The formula was simple: make a movie for a few million bucks that capitalized on current fads or fears, and get out. Accuracy was never even thought of.
This, of course, was in an age before video stores, when any piece of garbage committed to film would ultimately make a profit, one $1 rental at a time.