It's not like the gov't has any problem locating people -- IF they are people that the gov't actually wants to find.
Even if the US military needed a draft, it might not do much good.
"Pentagon: 7 in 10 Youths Would Fail to Qualify for Military Service"
That’s the other thing - if women can serve in combat units and don’t have to register for the draft, men should not be required to either.