Rape is one of the most difficult crimes to deal with in the legal system. It usually happens in private with no outside witnesses. Unlike almost any other crime, the same physical actions can be rape or lovemaking depending on consent. If there isn't serious injury, you can't proove that it was rape - some people enjoy rough sex, and some rape doesn't do much physical damage (some does). Being raped can cause lasting psychological scars for the victim. A false rape conviction will ruin the life of the accused. Rape often happens when one or both of the parties are drunk and don't have a good memory of what happened.

I don't know any way to solve this. I can only suggest that people avoid getting into situation where they are likely to be raped, or falsely accused of rape - in particular, don't get wasted at parties.

Just as a side note, the most common form of rape in the US is male on male rape in prison. It is almost impossible to prosecute, and causes severe trauma for the victim.