I know nothing about he statistics about rape reports being proven true or false, but I don't think it's comparable to robbery or murder, because in the case of rape, we know that the vast majority of victims knew the perp. Therefore if an arrest / conviction did not occur in those cases, what would be the reasons? Cases where the perp could not be identified or found would be the small minority, so the rest would be what? Victim recanted or not enough evidence to charge / indict / convict?
Prosecutors sometimes have their own biases and won't prosecute on behalf of women who they think got what they deserved. Others sometimes don't believe they have enough evidence to successfully prosecute or don't think the victim is sympathetic enough. There are also some who would like to prosecute but know their judges and jury pools well enough to understand that a conviction is unlikely and they don't want to put the victim through the trial. Finally, sometimes victims (and their families) decide going through a trial is not worth the expected outcome.
FWIW, when you see child molesters get soft sentences it is often for one, or a combination of, the factors above.
Edited by ChocolateReign, 24 October 2017 - 10:18 PM.