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).
Owning a vehicle is already a necessity. That and trucking make a lot of the highway infrastructure needed already so there’s less incentives to invest elsewhere.
Also can’t really think of many places a large number of people over the day need to transit back and forth. And if there are cases - there might already be a train or bus route.