Same reason a lot of guys go in — job training, good benefits, etc. I don’t know where she’s from but a career in the military where she could gain some job skills and decent benefits probably sounds a lot more appealing than waiting tables or making minimum wage at the local Wal-Mart. I think women can effectively serve in administrative positions.
You know, I really have no problem with this except for the part where women have to pretend that they are equal to men in combat roles. And, where training and discipline rules are relaxed from what they were as late as the 1970s.