Because they've been taken away their "life". And, so many people don't believe it. Most of women don't even report it. It's (grrr).. well.. i'll keep to myself.
many powerful men are rapists, so you have to be aware that they have their allies. Like women who are raped in the US military have something like a 2% chance of getting any sort of justice. Also many men think women call rape just to punish men, and so many trails first try to call the victim a **** who wanted it. And in some places, you have to pay to get a rape kit. So many victims never come forward due to all the horrible things they would have to go through in investigations and trails. Often you can't prove you were raped.
if you want to learn about rape in the military, watch "The Invisible War" http://www.stripes.com/news/us/documentary-unveils-rape-in-us-military-with-testimonials-1.179411
Deep down the shocked people don't want to deal with it?