I don’t think this is the cause of it though: No money for buying cars. My guess is, it’s because there were more alternatives such as trains and public trams and cities are more densely build out of history.

Despite the US, Germany(& Europe) and Japan had a huge railway network spanning all cities and even smaller cities. The area I lived in Germany had the first railway 1840. Japan 1872. US 1827. However, if you look into the network expansion the US never reached the density and complexity of both others due to it’s sheer size.

With the advent of trains all bigger European and Japanese cities began to build public tram systems. To such an extent that it spans most of the citied nowadays. This is still not the state in US. One can literally see the difference when visiting US, German, and Japanese cities todays.

Moreover, US hadn’t cities that grow organically throughout the centuries. And there is much space available. No dense historic city centers, no growing city rings. E.g. you can easily cross an one million city such as Cologne by bike in 1-1,5 hour. (And adding traffic jams and parking lot search time, bike is more efficient and easy)

Interactive map railway network Germany: https://interaktiv.morgenpost.de/bahn-schienennetz-deutschland-1835-bis-heute/

Video railway network Japan https://jref.com/threads/video-150-years-of-japan-railway-network.504981/

Video railway network US https://youtu.be/a8lX5A2q-Eo?si=-zjdLE1Wz8TlyCbt. Wiki https://en.m.wikipedia.org/wiki/History_of_rail_transportation_in_the_United_States

Public tram systems in US https://en.m.wikipedia.org/wiki/List_of_streetcar_systems_in_the_United_States