It's less-lethal, not nonlethal. Even blanks can be deadly. A gun should only be pointed at something you're willing to destroy.

Cops are not held to as high of standards as everyone else. This should not come as a great revelation.

That's not very american of you. You have to be ready to shoot and kill anyone apparently

If you go through a defensive carry class you'd almost certainly be discouraged from doing that by the instructor for multiple reasons:

First is that all ammo can be lethal, even blanks. So if you're not willing to kill to protect your own life, that may cause it anyway. On the flip side, a prosecutor will argue that if lethal ammunition wasn't required, then use of a gun wasn't necessary and you've not only broken firearm discharge laws (in place where most people live), but are also guilty of assault with a weapon with intent to kill or maim.

Firing a gun in self-defense is only warranted if nonlethal means are insufficient. If you try using less-lethal ammo and it doesn't stop your attacker, you're killed or seriously injured. If you try using less-lethal ammo and it does stop your attacker, you're still screwed by the legal system (possibly except under some "stand your ground" laws).