Most people end up getting married and having children, and women are the primary care givers of those children. The aviation industry is not family friendly when it come to working hours with aircraft operating 24/7, 365 days a year. Frequent extended periods away from home and call outs at short notice are normal.
An aviation career will usually involve several relocations often to less desirable locations in remote areas. Even if you go airline straight away, you probably won’t get the most desirable city base and upgrading to Captain can involve another move. Just ask Virgin Australia pilots about getting a Brisbane base.
Medicine, aviation and most other professions require the hard yards to be put in but once qualified as a doctor or lawyer you are likely to employed relatively quickly in a well paid job in a location of your choice. Get a CPL and you will be lucky to get any job, are probably going to have to move and will only get paid award wages.
A doctor has many different opportunities available, they can work for the RFDS, work on a cruise ship, enjoy flexible working arrangements at a 24 hour medical centre or major hospital and specialise in an area which interests them just to name a few.
Job security is incomparable without having to worry about annual medicals or base checks. Changing employers at any time isn’t difficult and doesn’t involve joining the bottom of the seniority list. How many doctors have been stood down due to COVID ?
Possibly there are so few women in aviation because they make better career choices.