I can often get somewhere fast during rush hour in Beijing on the subway rather than a taxi. But Beijing’s traffic is Superbad compared to the USA. The city is also huge, but they have just done a good job building it out everywhere.

The same with most big Chinese cities (smaller cities have taxis, so you still don’t need your own car). Tokyo’s system works ok as well, although I’m not sure if taxi would be faster since it is too expensive for me to try. The subway/loop lines are good enough to get places as quickly as I don’t think taking a taxi would save much time.