With male applicants vastly outnumbering female ones for pilot jobs, it is much more likely that a suitable female will find herself employed as the company can easily knock back 90% of male applicants but cannot knock back female ones at the same rate or they wouldn't have any women pilots.
An operator with a 100% male pilot group which had female pilots apply but had rejected them could face accusations of discrimination, and they know this, hence the acceptance rate for female applicants will be much higher than for males as they need to be represented in the workforce.
A company might be willing to accept an applicant who is 80% of what they consider ideal, but in an employers market might easily be able to fill vacancies with candidates who are 90%. It is quite possible that a lower scoring female would get preference over a higher scoring male as long as she was above the minimum acceptable level, in order to ensure an adequate level of representation.
If 50% of applicants were female and of the same standard as the male applicants, then the rejection rate could be the same and 50% of the workforce would be female. When something you need is in short supply, you can't afford to be too fussy.