Short answer: cities are too far apart and the USA is large. However, how much funding is there to really implement the same thing that exists in Japan but in the United States? Also, is there an incentive for that in the first place? What about population density? Japan is more compact regarding their population density while that’s not the case for America plus both Osaka & Kyoto aren’t too far from each other (but Miami & Washington DC are distant).
Ehhhh, I tend to think the distances are less important than the fact of the infrastructure being prohibitive to set up.
Trains like that can’t just be dropped onto the existing rail network. I mean, even if the rails p tracks we have would allow them to operate at speed, it would be a nightmare getting them to mesh with existing rail traffic. You’d lose the high speed factor, defeating the purpose.
So, even in individual states, where the distances are closer to what you’d see in japan, it’s not a net practical solution without some serious rejiggering.
You could likely get some lines done anyway, like from D.C. to a few major cities on the east coast. But would there really be a benefit? Would it reduce highway traffic significantly? Would it be safer and more efficient than existing passenger rail? I genuinely have no idea, but there would be a need for that kind of thing to make it worth building out. If it’s just shifting a small fraction of city-to-city commute, I don’t know that or would be worth the massive project it would take