Where's the lie though?
Without blacks and the crime they bring, white flight would have never happened and rather than stalling in the 1940s, US urban rail transit development would have likely continued to press on as it did between 1850 and 1950 more or less unabated. You don't need highways to get into the city from the suburbs when people had no reason to leave the cities in the first place, and busification of the trolley lines would have never happened if the middle class folks who they were built for were still there to raise a stink about the tracks being torn up.
All of the US's postwar transit fuckery boils down to whites not wanting to live near black people and not wanting to give the blacks in cities any easy means of getting our to their suburban redoubts without a car.
If the US was as ethnically homogenous as Japan, we likely would have seen just as much postwar urban passenger rail development as Japan did.