[someone123]

There was a transit and urbanism "recession" in most of North America for most of the postwar period so I think that led to the sense that the only way to move those things forward was to add a lot of population, so much that those things go up in aggregate while they go down per capita (kind of like our economy right now).

In a lot of old parts of Europe there was gradual organic improvement of structures and infrastructure even sometimes without much population growth for long periods (due in part to high death rates). Some small town could remain a small town and get ornate stone houses, grand public buildings, railways, etc.