The public and private shaming of rape victims when they report the crimes is exactly the reason so few girls and women feel safe or comfortable doing so.
"Only about 2% of all rape and related sex charges are determined to be false, the same percentage as for other felonies (FBI). So while they do happen, and they are very problematic when they do, people claim that allegations are false far more frequently than they are and far more frequently than for other crimes. Put another way, we are much more likely to disbelieve a woman if she says she was raped than if she says she was robbed, but for no good reason.
On a related note, only about 40% of rapes are ever reported to the police, and this is partly because victims know that if their claim becomes public, their every behavior will be scrutinized, they will be shamed for their sexual history, and they will be labeled as lunatic, psychotic, paranoid, and manipulative. Just because someone does not report their crime does not mean it did not happen. Furthermore, only one in two claims lead to prosecution, so if the DA decides not to prosecute, that says nothing about whether or not it happened. (http://www.rainn.org/get-information/statistics/reporting-rates