Those who are able to afford to live in affluent areas have high income jobs and can purchase the land surrounding their workplace, enabling non motorized conveyance or transit. The low and middle class, are forced out of the area, however these middle to low income jobs still exist and they need to be accomplished; think how far out a janitor is pushed away from a high income residence area before they can afford a…
You're describing a chain of events that happened, but doesn't necessarily had to occur. Firstly, the mechanism you describe where people bid up housing near transit corridors also happens near highways and traffic corridors, though it is more dispersed. This effect can and has been mitigated by combining rail transit with buses or trams leading to rail stations. It is of course more effective in less suburbanized ar…
Don't forget that these stretches of black asphalt act as giant heat accumulators, soaking up the sun during the day and keeping temperatures uncomfortably high after the sun goes down.