It's not "universal". Suburban city-planning is a US thing, almost exclusively (I'm told Canada follows suit). Most cities allow mixed commerce-living. Meaning

It's not "universal". Suburban city-planning is a US thing, almost exclusively (I'm told Canada follows suit). Most cities allow mixed commerce-living. Meaning there's offices, shops, factories in-between and below housing. Yet US suburban planning -by law- disallows offices (and shops and factories) to be mixed with housing. You are often literally not allowed to live close to work (or work close to your home). that isn't universal at all.