That's a big part of what people don't realize - city centers and old neighborhoods will have houses of vastly different ages (my town's center has houses that were built this year next to houses that are almost 200 years old).
But most of the houses in America aren't those. They're in developments of different ages, and the houses in those developments look roughly the same. You might notice some differences in the very old 40s developments, because of 80 years of additions and remodeling, but most of the houses will have survived and few will have been rebuilt.
When a city builds up slowly, you get many different things mixed together, and that is more interesting.
But most of the houses in America aren't those. They're in developments of different ages, and the houses in those developments look roughly the same. You might notice some differences in the very old 40s developments, because of 80 years of additions and remodeling, but most of the houses will have survived and few will have been rebuilt.
When a city builds up slowly, you get many different things mixed together, and that is more interesting.