> As somone who's lived in different European and Japanese cities it just saddens me that highways replaced local public transport in many American cities rather than added to it.

The population density and distribution of that density is massively different in Europe and Japan than in the US.

For effective shared or public transit, you need transportation hubs that are a convenient distance from where people are and where they want to go. If people and population centers are very spread out, then the transit becomes both more expensive and less useful. Even if you can take rail between two population centers, odds are good that you'll still have to drive a long way to the train station then drive another long way to get where you're actually trying to go. Because there's not a lot of population, transit can't run frequently without being a massive waste of energy, so schedules become less convenient.

Check out this density map:

https://dhs.stanford.edu/wp-content/uploads/2011/11/popdensi...

Note how Europe is consistently dense over a very large area, with a core of highly dense areas all fairly close to each other like London, Paris, Brussels, Amsterdam, Munich, and Bern, while the adjacent regions like Italy, the Balkans, and even Poland have fairly consistent population density. In Japan, the density is highly concentrated on Honshu, and even then it's concentrated into certain cities and prefectures.

The US, meanwhile, has only a few dense regions, mostly in the Northeast, with the rest of population centers spread out very large areas. Not coincidentally, those more densely populated cities tend to have more public transit than the average American city. There are notable exceptions, such as Los Angeles, but LA is not representative of most of the country.