We understand. What you don't understand is that in the case of a rape trial preponderance of the evidence usually means kangaroo court--and that's before the universities try to keep the accused from defending themselves.
How do you propose the accused defend himself beyond "I didn't do it"?
Rape trials can be complex.
However in recent years, which I believe is that a woman can withdraw her consent at any time. In other words saying 'Yes' to begin with should not be a legal commitment, even if they are married.
As for consenting when intoxicated, the prosecution case would be that the woman who consented (if she is pressing charges) was of unsound mind due to intoxication, then consent was invalid.
In the case where he claims he did nothing, then the accuser should produce forensic evidence but this may not always be possible. It would be one person's word against the other in the absence of witnesses. Frequently a person falsely claiming they 'didn't do it can be caught on a lie, slipping up by mentioning something did happen. Likewise a female may slip up.
I am sure genuine rapes charges failed to achieve a conviction and some genuinely innocent people may have been convicted