My kid is 2. New York City and most EU countries (including Spain, Portugal, UK, France) allow children to ride in taxis without a car seat.

This makes it far more practical for people to live without a car - hard to imagine in most of the US I know. As most such trips are low speed around town (e.g. getting to and from a train station or airport) it seems a reasonable trade off.

You of course need a car seat in a private car.