My grandfather said that failure to fire got a lot of new soldiers killed in Europe as well. He said that they just couldn’t comprehend that someone they didn’t even know, wanted to kill them.
Those first reluctant and dead soldiers provided a powerful motivator.
Another point that brings up is that a lot of the folks that might be co-opted into the Obamarmy would be youth who've played a hell of a lot of first person shooter games, and those games are fearsomely effective at training people to aquire and engage targets. That has proven itself out in that youth "rampage shooters" accumulate way higher body counts than people over about 30 or so. Something to think about...
“...in any given firefight, about a third or more of US troops did not fire their weapons at the enemy.”
Not this nonsense again! Trust me, in any given firefight that I was in in Vietnam, it would be rare for 2/3 of the troops to be in a position to point their weapons at the enemy, or even to know where the enemy positions were. As well as being uncertain where our own troops were, so as to avoid shooting at our own men. Proper fire discipline: don’t shoot when you don’t have a target, and a clear field of fire.