The onus to provide evidence falls on the one who makes a claim, and the one who denies (the same) can absolve himself or herself by making a solemn oath to the contrary.
Rape victim: He raped me!
Barbarian rapist: I solemnly swear I did not.
Judge: Case dismissed.
Also: TheReligionofPeace - Islam: What Must a Woman Do to Prove Rape?
"And those who accuse free women then do not bring four witnesses (to adultery), flog them..."
You know, it's pretty funny how you left part of that quote out. The relevant passages are referring not to a woman claiming she was raped - they're referring to men accusing women of adultery. The "onus" is on the men to prove that the woman was unfaithful, and they must provide 4 witnesses - not the other way around.
Again....The Stoning Of Soraya. 4 witnesses could be anyone. Neighbors. Friends. Even the children of the woman in question. How to get rid of a wife so scumbag can marry younger, newer wife? Accuse her of adultry. Get friends to say she was lewd (make sure you have coin in hand), dig hole. Make pile of rocks. Holler for Sunniman in his cowboy boots.
There's no question that people lie, and I'm certainly not defending Sharia governments - but there's no need to lie about the scriptures.