This article has a quote from the Police Chief that Palin hired admitting that he and his department billed rape victims. The Police Cheif whom Palin fired before him says that during his tenure, the city paid for the kits...

http://www.cnn.com/2008/POLITICS/09/21/palin.rape.exams/index.html

I would imagine that the prospect of having to go through a lot of red tape to get their insurance companies to pay for the kits would also deter a lot of women from reporting their having been raped.