OK, educate me here regarding pistols and the US military.

[Clutch]

One thing I've never fully understood about the military is why only officers above a certain rank (Sergeant, I believe, though I might be wrong) are issued the M9/92FS or M11/P228. Don't all recruits and trainees go through weapons familarization and training with handguns and rifles/carbines alike? And if so, then why not issue them those weapons from the start, especially if they're going to be sent into a combat zone? Or do they and I'm just reading wrongly into things here?