SJSinNYC,
It could be there is a very specific reason, but according to what I think (no basis, just making up) I would imagine that they consider it a man’s job. A woman sits in the back or in the passenger seat and the man drives. I guess it’s a way of having the woman being more passive then active. I don’t really have a very good explanation and as I said, I am very happy to be able to drive and don’t think there is something majorly wrong with it. I do respect those who have this minhag/chumra/meshugas, (I hope I included one of the right words so no one corrects me that it is a minhag not a chumra or vice versa, we gotta be very careful with the technicalities around here…:) as believe I am open-minded enough that I can accept other people’s belief’s even if I think it’s fine.