The females can pull off a victim type stance. That the boys seduced them and that they're sorry and willing to accept punishment for their loss of control. If a judge gave the maximum punishment after a statement like that, the public would eat him alive and probably call his decision sexist.

I also think it is because they believe that young boys aren't mentally hurt as much as young girls are, so there is less damage done and so less of a punishment is required.

I'm just tossen out thoughts.