Earlier quoted context omitted.
> The density of the NE is nothing like what you see elsewhere in the world, especially Asia, and Japan and China specifically. Yeah, I defy anyone who claims the US can't build trains "because of density" to fly to Tokyo, and actually take the Seibu Shinjuku line west from Shinjuku station. Look at those buildings built right next to the tracks , for many, many kilometers. People live in those -- if the windows open…
I think a big part of it is also that (partly because of the necessity of building for earthquake resistance), Japanese construction is a lot more robust than American housing, and also tends to have extremely good soundproofing on windows and doors. Actually, it's most of the rest of the world, except the US.
(Which is why we're now tearing down our old house and building a new, stronger one. Post-war Japan was more concerned with a) building a lot of houses, and b) keep lots of jobs, which meant, as far as houses were concerned, building use-and-throw-away houses. Then build another. And another. And don't talk to me about sound proofing.. it's non-existing. What with no insulation in walls.)