They would need to build proper public transport first. Most of the US is far, far behind other countries there, but many other first world countries are still

They would need to build proper public transport first. Most of the US is far, far behind other countries there, but many other first world countries are still completely impractical to travel by public transport too. e.g the UK, where while trains go most places, they are notoriously slow, unreliable and expensive and do not run in the very early morning. Even countries people might expect to have good transportation (e.g. Germany) see the same problem to a lesser extent, rendering its day to day use impractical. The real answer is to have guided taxi-style individual vehicles that people can book, take to whereever, which then leave to pick someone else up, giving the privacy, speed and convenience benefits without the parking and traffic problems, but the technology isn't there yet to implement them in a real city.