Military-tech people really really want there to be knockout gas (like in The Prisoner) and harmless stun guns. And I think that's why there won't be any such thing, because the sheer desire to believe that the prototype you have in hand is the thing you want, means that the kinks never get ironed out.

So the Russians in that theater-hostage thing used their "knockout gas", but oops dozens of people just dropped dead. And dorks in uniforms love their "stun guns", but I bet being "stunned" with one of those things is no more harmless than being whanged on the back of the head with a lead pipe.