The number of wifi networks that're running around us has gotten so crazy that it's no wonder we all need wifi-6 to even get reasonable speeds. I'm the kind of person who goes around and disables wifi absolutely everywhere possible, so this is good to know, but what'd be even better is if devices stopped running wifi networks behind our backs. Sigh.
I guess that's because people here tend to use 5G mobile networks and not so much WiFi, maybe not at all, so there's little contention. (Perhaps this makes it obvious, but not in the USA.)
Instead large houses need signals that go through roofs, floors and walls. But they probably also have a lot of family members inside, each one with their one, two or three wifi devices that interfere with the rest of the family. Maybe one repeater per room and 5 or 6 GHz would be good there too. 3 different video streams to people of the same couch could still be challenging.
Check out the table on wikipedia: https://en.wikipedia.org/wiki/Template:Wi-Fi_generations