Infantry units tend to maintain their weapons because their sergeants make sure they do, as the M-16 (or whatever) is the primary tool of their trade to accomplish their mission. That isn't the case with transport, artillery, clerks, whatever. Their sergeants are ensuring that trucks, tubes, computers, whatever, are maintained as they are the primary tools of that trade. Any extra time they can use to work on their personal gear (M-16), or, possibly, sleep. If they'd put their own weapons before the mission, they'd have some pointed words directed at them.
We're focused on the rifles because of our interest in the general subject. I suspect the run of the mill infantry guy isn't particularly, much less the support folk. The military, as a whole, is even less so. Infantry invests territory, preferably without fighting for it, after it's been engaged with artillery, armor, and air power. The military puts its money there.
M-16s are more than defensive weapons, but not much more; it's the difference between being "engaged," and "closely engaged." The folk at the sharp end need something that will go "bang" when they need it to. We owe them that, even if they were too tired to clean it properly.
Jaywalker
