In non-pandemic times, HK people live like people in any other city; they usually don't work where they live, and often times they don't necessarily do all their shopping there either, because people like variety. (Although with how crazy the real estate was getting in Hong Kong, I remember each visit that it seemed like each mall was slowly turning into the same chains and whatnot in every one.)
That's just normal for the rest of China as well. HK still has much more retail diversity than say Shenzhen, but the gap is closing quickly.
At least in HK it's particularly bad in the new town areas like Tsueng Kwan O and Ma On Shan, since there isn't really much traditional non-mall retail to begin with in those areas.
Having one building house hundreds (or thousands) is normal here, and these days new properties developed tend to have shops and malls below the residential apartments (more $ for the developer), but IMHO the lifestyle couldn't be more different than what is described in the article.
It used to be the case a couple decades ago that people in public housing poked into their neighbor's businesses sometimes, but these days even if you live in a huge apartment building everyone minds their own business.
Very few people live and work in the same building, or even the same district (due in part to zoning). The signature feature of Hong Kong life is trying to cram yourself into a crowded bus or metro train (which is presumably also true of most other Asian large cities). There's a big difference living in a small town with a couple hundred people, and a dense city of millions.
I honestly don't think most Hong Kongers (that includes me) would last even a week in the Whittier winter.