Good point Whirlygig!
Maybe I just had bad luck in flying with female copilots who were not properly qualified.
RvB, here's an example for you:
A few years ago, we had to train a mixed crew for a charter company. On the first day of sim training, the guy comes up and says to his female sim partner: "I have had very bad experiences flying with female pilots, so I would like you to know that if I get upset with you, it's nothing personal. Just bad experience."
The outcome of the week of sim training was that she had passed the course with flying colors, while he needed some extra work.
I am sorry to hear that you've had some bad experiences, but don't generalise.
Nowadays, the number of female pilots is still very small, which "causes" those bad experiences to startle you. I am sure, however, that you've had the same number (or even more) of questionable male pilots sitting next to you.
Regards,
TG