Because according to this prosecutor below, the percentage of false accusations of rape is close to half. And he says demonstrably false, not simply 'not enough evidence.'

http://boysmeneducation.com/avfms-mega-post-10-reasons-false-rape-accusations-are-common/

"For 16 years, I was a kickass prosecutor who made most of my reputation vigorously prosecuting rapists. I am unaware of any Colorado prosecutor who put as many rapists away for as much prison time as I did during my prosecutorial career. Several dozen rapists are serving thousands of years as a result of my efforts. However, during my time as a prosecutor who made case filing decisions, I was amazed to see all the false rape allegations that were made to the Denver Police Department. It was remarkable and surprising to me. You would have to see it to believe it.

Any honest veteran sex assault investigator will tell you that rape is one of the most falsely reported crimes that there is. A command officer in the Denver Police sex assaults unit recently told me he placed the false rape numbers at approximately 45 percent. Objective studies have confirmed this. See Purdue Professor Kanin’s nine-year study published in 1994 concluding that over 40 percent of rape allegations were demonstrably false.

The above statements are heresy to say publicly for many politically correct prosecutors. That is especially true if they want to maintain good relations with the victim advocacy community"