There is still a stigmata on rape vicitms, especially women as to who was responsible for it occurring. How they were dressed, how they acted, if they had been drinking, if drugs were invovled (voluntary or not), etc. This makes women, especially young women reluctant to come forward to file complaints. There is also the psychological aspect to the act. Did she know them, what did she do immediately afterward, was evidence preserved, etc and if not why did she not do so. The laws have been getting better at protecting the victims (no matter what gender or orientation) and all reporters such as universities have stopped turning a blind eye to the victims and are now trying to support them.
