For every Crystal Magnum there is a "Marie." There was a ProPublica article called "An Unbelievable Story of Rape" that takes place across two states and several years. She claimed to have been raped, then recanted after aggressive interrogation. She was charged with a misdemeanor. Some time later it became obvious that she had been telling the truth. There are a number of salient points that could be taken away from this case.
If we were to charge people for making false accusations, there will be wrongful convictions. One should also take into consideration that a penalty for making a false accusation might discourage someone from recanting and instead pressing forward, the results of which would be unpredictable.