If they are only asking females for ID, to link the gun to the owner, perhaps they are looking for straw purchasers. Wives/girlfriends buying guns for their prohibited husbands and or boyfriends. Not saying it makes it right, but it's a legitimate possibility.
Good observation. After all, my wife was asked by the employee "is this for you ??"...
She very calmly and without missing a step, replied "yup "
Personally, I'm more worried about being shot by a woman than by a man.
^ this
My wife is an amazing shot, and she physically can't raise a gun up to use the sights (100% not kidding !)