State legislatures like to lower taxes. To do this, they decrease services where they can. There are not enough well informed insane people to vote them out of office, so they have closed mental health services, and just prescribe pills. Some of the pills have disturbing side effects, and the patients stop taking them.
The police are poor shots and shoot to kill. They are very very good at defending themselves.
There is no complete solution to this problem, and the solutions that do exist are expensive. It is better just to slash services so that each state can lure companies by giving them free facilities and juicy tax breaks.
