By the rest of the world you mean Europe, right? Because outside of Europe it’s not really the case. Granted, i’ve not visited every country on earth, but in most cases i’ve seen “small livable downtown” is mostly an European thing. In other cases, you will need to take a looong ride home from the downtown (1h+).

You can attribute this to the economics of the Renaissance pre-modern Europe. Most regions and peoples of the world imported modern economies to go straight from Dark Ages to globalism. Europe somewhat uniquely transitioned to dense, walkable mercantile centers during this period before spreading the system abroad, whether by sword or ship.

"The Civilization of Europe in the Renaissance" by John Hale is a great, lengthy reference here.

Did you reply to the right comment? I never said everyone gets to live in an idyllic neighborhood that serves their needs for housing, work, and entertainment. What I said is it is possible to live near rail and transit but not air.