I think previous posters who commented on the simple geographical differences hit the main reason rail is more effective in Japan than the US. Japan is basically a bent straw - you could put a line running north and south down the eastern coast with spurs running west at key points and service country relatively well.
The US is a giant rectangle with it's major population centers located randomly within the rectangle. geographically rail could work regionally (California is kind of a reverse Japan) and on the East Coast rail could be effective between Boston to DC but a national system that would replace air travel would be logistically problematic. California is a highly populated state which happens to have the Sierra Nevadas followed by the Rockies cutting it of from the East. Less populated northern states would be challenged to make the investment of rail service challenging and let's not forget may of those area spend a lot of the winter buried in snow - so track maintenance becomes an issue. And as others have commented - we Americans are an impatient bunch - if you don't live in a major metro area that would serve as a rail hub your not going to want to have to make three transfers to get to Point A to Point B.
Having a plan to upgrade facilities, transportation systems and manufacturing process to more ecologically friendly technologies - as occurs now is a prudent path - and there is no harm in seeing if it can be accelerated. The kindergarten management proposal of the green new deal imposing an illogical time deadline with no consideration of whether it is economically, technologically or logistically even feasible (I know the world's going to end, you don't worry about being factually correct, be morally right and just do it!) is reckless at best and stupid at worst.
It's hard to even fathom just the resource expenditure in raw materials it would take to satisfy a national rail system, charging stations for electric cars "everywhere" and upgrades to every building in the country. Imagine the amount of raw materials that would be mined, the fossil fuels burned fabricating the materials and the amount of scrap materials generated just to make us "green". There comes a point where maintaining or upgrading a technology no longer provides a return on investment - that's the time to convert to a new technology. Artificially imposing deadlines would simply be disastrous and wasteful.
As with most issues it's hard to find someone articulate a reasoned position - because unless you're claiming the world will end in 12 years or we shouldn't worry and you can go grill a side of beef over a tire fire you can't get any attention. But I will tell you again - there are some smart people out there figuring things out (look back at the changes from 25, 50, 100 years ago in medical, transportation, communication and manufacturing) - it's going to be OK guys. So when we get 4" of snow and the media and politicians become hysterical and everyone makes a run on the milk, bread and eggs so they won't be forced into cannibalism sit back, grab your Swiss Roll or Nutty bar and an IPA and binge watch that TV series you need to get caught up on.
Wendall : That's very linear Sheriff
Ed Tom : Age will flatten a man Wendall