These are all nice solutions to reduce the number of cars in a dense urban area, but I'm going to go on a limb and guess the author doesn't have to deal with installing and uninstalling cumbersome carseats in every car they use.

Once you start moving around town with little ones, the whole equation changes. We try to be as lightweight as possible, but there is still that stupid carseat. I've tried using Uber for a week in a different city and got really good at installing a carseat in 60 seconds but it's a big hassle. And you have to carry the carseat with you when not in the car.

If the city is dense and there is a desire to reduce cars, this is where public transit shines: your children can either walk or be carried (backpack carrier FTW) without any of the setup/teardown at every single stop. Bonus point: no need to strap/unstrap them.