Japanese passenger rail, by which assume you mean the slower trains and not shinkansen (because shinkansen is in another world of superior experience), is comfy as fuck and reasonably priced. As someone who rode Amtrak, you know neither of those are the case in the US.
I have taken an Amtrak train between Houston and Dallas and it sucked like all passenger rail sucks. Yes, even Japanese passenger rail sucks.
Take the fucking L.
Japanese passenger rail, by which assume you mean the slower trains and not shinkansen (because shinkansen is in another world of superior experience), is comfy as fuck and reasonably priced. As someone who rode Amtrak, you know neither of those are the case in the US.