False allegations do happen, although I have no idea how regularly.
https://www.montrealgazette.com/news/article620901.html
The article above outlines a situation at McGill in which a student executive was accused of sexual assault publicly, although never charged. It was claimed that the sex was not consensual and the girl was too intoxicated to consent.
The student executive was fired, forced off his sports teams and socially ostracised from campus. Many months later, text messages from the girl indicated that she targeted him for sex that evening in order to get his job.
This is just one example, but essentially I think the judge was correct to take each case a face value and not blindly ‘believe the victim’. The truth is rarely black and white, and everyone deserves the presumption of innocence, even in the court of public opinion.