And that’s precisely the problem, because cars don’t scale well. Suburbs surrounding large growing urban areas in the US are often clogged with traffic. Just look at the Bay Area.
You could say the solution then is to decentralize and make it so everyone can have the light traffic car commute. Aside from possible environmental impacts (Who knows, there might not be any with all the reduced traffic from this scheme), I don’t think this is realistic right now; humans have clustered around cities for literally millennia.
Edit: I live within a few minutes’ walking distance from several grocery stores. Typically I just buy a bag’s worth of groceries at a time. Physical ability differs, of course - but that’s another argument for reducing car use in my view, so you can clear the roads for the people who truly need the car.