Sparkly, no one makes up halachos about women not driving. In some communities, the accepted minhag is that women don’t drive. If someone chooses to consider herself a member of such a community, it is possible that halachically it is assur for her to drive, since there are halachos about minhag hamakom and listening to one’s Rav.
You do have to belong to such a community, and you do not have to understand their minhagim either. What you do have to do is to learn to respect other’s minhagim even if you don’t choose to follow them. I personally would not want to be part of a community where women are not allowed to drive, but I have no problem respecting them and I certainly would not go around criticizing them in cyberspace.
You would be upset if they told you that it is assur for you to drive, so don’t tell them that they are doing something assur by not driving. That is the epitomy of close-mindedness.