A question that needs to be asked is why do officers feel they need to shoot to kill, as opposed to shooting to incapacitate?
That's an awesome question that I asked my partner when he began his police training.
It's because, at least in Canada, police are trained to 'one up' the weapon that is being used against them. Ie if a person tries to punch a cop, the cop will use his baton. If a person has a deadly weapon (gun, knife, bat etc) then the cop will use a deadly weapon in response.
As well, it's not realistic to train police to shoot at limbs to try to incapacitate a person when their own life is at risk. There are studies done that show when an offender is running at you there is a certain amount of distance where it is plain and simply too late and you will, unfortunately, get shanked if you do not shoot and it does not drop the offender.
As for pepper spray, it's generally a huge misconception that it will debilitate everyone. Most people are able to attack after being pepper sprayed, especially if they have adrenaline pumping and are attempting to be violent.
Police are not trained to respond to a gun threat with pepper spray.
My understanding is that the cop assess the threat level and is trained on how to react to that threat. Unfortunately the sheer amount of unarmed black men that are killed in the States shows the absolute lack of ability or care to properly assess the situation.
But like I said, this is how it is in Canada, not America. I am aware that our police force requires significantly more schooling and training than in America to the point where you can barley compare the two.