Simple point.
(1) Hand the police a weapon that can and does kill.
(2) Tell them it's "non-lethal"
(3) Any associated deaths are then "accidents"
Training can only do so much, and human nature and emotions can and do short-circuit the training.
We should be treating each death as accidental manslaughter, and charging the officers who kill. Every single use of the taser should be treated as assault, and charges laid, unless it can be clearly demonstrated as a life-saving, no other option, necessity.
We need to make the police reluctant to use it unless they absolutely have to, the complete opposite of the current situation. The operating mind-set seems to be "why would any cop risk getting a bruise or two when they can stand back and "zap the sod"?
Faced with assailants with knives or guns, fair enough, but no other excuse seems justified.