As the sister comment said - the houses are just strong enough not to fall over in a "normal", all-the-time earthquake. Our house sways a lot under typhoons and far-away earthquakes (far away = long wavelengths). It's only relatively recent that building codes have been updated to handle real earthquakes without falling over like a house of cards. Remember the Noto earthquake Januar 1, 2024? Large areas didn't have a single house still standing.
(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.)
When I lived in Japan it was in a relatively recent (last 10 years) but not brand new apartment block - Maybe if you are talking about a rural area or an old postwar Showa era house, sure. But either way the sound proofing is worlds better than any new construction in the US.
I'm in a 20 year old two-storey apartment right now (while we're building a new house), and the sound-proofing isn't non-existing but not as bad as some other apartments I'm aware of (where you can't make a sound without the neighbors start knocking on the walls/floors, and you're privy to thing you don't actually want to hear..) - but we can hear every footstep when the neighbors walk the stairs to their upper floor. The rooms which are more distant are fine, we don't actually hear them talking. Most of the time.