Buying the tech from Japan isn't gonna solve the fact that you don't even know how to manage a normal passenger rail line, buddy!
Also I know this is technically a Japanese news site reporting from their perspective, but the US is still seriously considering this on their end, just like how they've been considering it since Japan first introduced the SCMaglev prototype decades ago.
It takes 4 hours to take Amtrak between NYC and DC. The same amount of time as it takes to drive, which costs a fraction of the money. I would believe that someone made an economical flying car before I'd believe the US suddenly has a working maglev line between two major cities.
The northeast corridor is densely populated and fast trains require very straight tracks. In a place like China, eminent domain is easier and the State can expropriate land for the construction of a straight track, but in the US this is harder due to higher costs (lower economies of scale) and endless bureaucracy for infrastructure projects. So I suppose they just found it easier and a better option to build a lot underground.
I wonder if it has something to do with surface exposure to magnetic fields. A very strong magnetic field, enough to levitate a train, zipping by you at the speed of said train, while not harmful to human biology unlike a lot of fear mongerers claim, can interfere with radio antennas and the navigation systems on ships and aircraft. The inside of the train is heavily shielded but I imagine it's pretty much impossible to prevent it from escaping into the outside without containing the entire track in shielding.
Management is indeed a different issue from building. Germany builds (or at least used to build) passenger trains - Siemens worked in conjunction with Russian railway and underground to create trains currently running in and around Moscow.
But ask any German about the Bahn and you'll see steam coming out of their noses.