Just because a case is dropped does NOT mean the accusation is false. Many women don't like the idea of spending three days in the witness box answering intimate questions about their sex life, plus being forced to describe the rape in full detail over an over again, and so drop the charges, for instance. In many cases there's not enough conclusive evidence for a conviction (or the prosecution feels so) so the prosecution drop the case even if the woman IS willing to be treated as a **** on the stand. In fact, it turns out the proportion of rape cases dropped before a trial in the UK is about the same as for most other crimes except murder. Are you suggesting that all those burglary victims weren't actually burgled? I'm sure a few are lying, but in the case of rape alone a lot of people take this to mean that all case where the case is dropped means that the accuser is lying.
M