> This is better and more easily addressed by car sharing services like car2go than autonomous cars.

This is not the conclusion I would draw from car2go failing out of North America. They still had the problem that you are required to find a legal parking spot and there's no guarantee that there will be a car available anywhere near you. Taxis and private vehicles solve the latter and former respectively but they all suffer from the inefficiencies inherent to the system design.

In the end the availability comes down to fleet size. car2go worked best here when they blanketed Seattle with Smart Cars, the fleet peaked around 750 and they were easy to find. After they switched to Mercedes exclusively the fleet was smaller and it became harder (though not impossible) to find them close by. My guess is that 2,500 cars would be enough to make them feel ubiquitous. A small fleet of autonomous cars won't mean it's likely one will be available to pick you up, and nobody has figured out how to deploy & maintain them at scale yet (I think Waymo in Phoenix is only running around a hundred vehicles).

The catch is the cost of parking: they weren’t hard to find here in DC but if you’re seeing lots of available cars nearby that means they’re paying a fair amount for all of that unused capacity. The Uber/Lyft model shifts that cost to the drivers so it looks cheaper as long as you don’t factor in congestion.

How do carseats for children work with these services?

BYO. Which is borderline OK for boosters (the Mifold [1] weighs under 2 pounds and folds to fit in a handbag), but totally impractical for a baby/child seat.

[1] https://mifold.com/products/mifold-the-grab-and-go-booster

Well you still need to park them somewhere, but yeah you could have less cars. And they don't work if you can't drive (or are drunk). And it is more complicated if you need one with a car seat or other special accommodations.