Half of households in the congestion zone are living at or below 3x federal poverty level ($70K for a family of three). One in six residents makes $20K or less a year.
really-rich people don't have to work/commute, so prefer to live in countryside with gardens
really-poor people can't afford cars, and rich(=busy) cities usually have accomodations for them -- so they live inside busy cities
There are lots of middle class commuters who can’t afford to live in the city: they aren’t lucky enough to win the lottery with a rent controlled unit, and are too rich to live in public housing, but still too poor to live in housing of a standard they can tolerate in the city even if their job is there.