i've only known two females in my life who didn't put me in danger when they drove, and that was because they paid extra attention to their driving, not because they were any good. the rest were either not at all focused on the task at hand, complete psychos, physically incompentent, or some combination of the three. i've driven with some male drivers who weren't very good, either, but i've driven with plenty who i felt safe with as well.
i think it really comes down to the ability of the brain to work with new sensory data and produce the correct changes in the enviroment. Your brain isn't hardwired to learn to see, hear, move, or any of that. They've done studies where they connect the eyes of weasels to the parts of their brains that the ears are usually connected to and the weasels learn to see. you can connect a camera to electrodes on your tongue and learn to see that way, too. Driving a car is the same thing, only with movements. To drive well, you have to have a brain that can adapt to a car and have it function the same as your body. Essentially your arms and legs simply become the muscles of your body, which is the car.
Your brain has to be able to detect your car rotating too much in a turn, process it and understand it instantly, and automatically produce the correct action to produce the desired effect, the same way you know you are going to fall, so you steady yourself. My experience is that girls don't drive this way (i'm sure there are exceptions, but this is based on my experience with people i've been passengers of). They drive the way old people play video games. Every action has to be thought out to some degree and they have no perception of what the car is telling them as they drive. They don't stop the car, they step on a pedal. They don't turn, they move a wheel. Obviously having a brain that can adapt to driving isn't the end-all-be-all, since even in our normal bodies, we can still fall down, drop things, bump into things, etc. But it sure beats operating everything by "remote" control.
pile that on top of choosing to not pay any attention and the usual driving-aggression that everyone has, and you've got a dangerous combo.