Kristof: Is rape serious?

Nicholas Kristof, in this NYT piece, wonders why rape investigations in the US are so desultory. It makes for very disturbing reading.

This links up to something I've been thinking about for a while: law enforcement officials in the US usually fall over backwards in haste when dealing with sexual crimes against minors (and understandably so). Why this apathy towards sexual crimes against women? Isn't there a worrying double standard in operation here: somehow, women who are raped aren't as deserving of the help of the State as those children who are. Is this distinction sensible?