Aren't the suburbs in the US essentially this, especially for the really decayed cities like Detroit and Baltimore? Many suburbs even have a lot of employment,

Aren't the suburbs in the US essentially this, especially for the really decayed cities like Detroit and Baltimore? Many suburbs even have a lot of employment, so the city isn't necessary for that. Another reason that cities are abandoned historically is that they become too hard to defend. In such cases, the people often relocate to a more defensible location. Similarly, in the US, many cities were abandoned by those who could afford it because of increasing crime, and they retreated to suburbs that were less hospitable to crime.