Strong emotion can cause a lot of stress on a person. When it comes to anger, it can cause them to cause harm to many things, even if they aren’t involved with the incident that made them angry. They will tend to be rash and do something regardless of the consequences. There is perhaps nothing more scary than an already low inhibition person becoming angry. A vehicle gives someone a lot of power, and having an angry person behind the wheel is never good.
In low income areas, people will tend to have less inhibition than normal, and they will tend to have less to lose. Thus when they become extremely angry, the fear of punishment does not have the same effect as it would have with a more well off person.