I can't refute this with stats, but I would not say I have seen the same thing either. I would be curious to know if different branches of the military have widely disparate demographics. I suspect the Air Force takes in the most highly educated and also wealthiest recruits, and that the Army takes in the least educated, least wealthy.
In the Marine Corps I saw big differences in backgrounds based upon MOS. My boot camp platoon was roughly 50% Hispanic and most of them ended up 0300 - infantry.
I remember when the PBS news show would list the causalities in Iraq every evening along with their hometowns. I perceived that most military members who died were from rural areas in the South and Midwest.
Is that still true? I thought it had changed post-9/11 (per [1]), has it reverted?
[1] http://www.heritage.org/research/reports/2008/08/who-serves-...