Your previous comment asked incredulously whether its mandatory to have a car when you have a baby, since the poster before you commented on mandatory car seat.
Now your current comment about taxis may enable you to put the whole puzzle together :)
So: how are you supposed to move children around, if you don't own or can't drive a car? You can't be expected to carry a car-seat around with you, as well as having kids in tow.
I had a car when I was raising kids; I've never confronted this problem.