[annouhMus]

But this isn't some sort of modern issue. They used to have carriages and rickshaws before and I'm assuming many women did take these modes of transport without a mahram.

But I would assume that there are always chances of fitna in transporting unaccompanied ghayr mehram women. Moreover with respect to women being accompanies by a male it is never sure whether they are related or are husband and wife. Therefore, I guess to be on the safe side, Muslim drivers should only transport men.