You expect so very little of the police. How very, very sad.
God I hope that you aren't an LEO. Your ideas on "the requirement" to use lethal force are not only illogical, they constitute de facto murder of the insane.
What is illogical is to believe that there is such a thing as non-lethal use of lethal force or that officers can be trained to “shoot to incapacitate”.
It would simply result in more shootings, more injuries and maimings, more deaths and more lawsuits.