One of the phenomenon studied due to the suburbanization of employment was spatial mismatch, that there was a mismatch between where people lived and where jobs they were qualified to get were located. Roughly, for various reasons, less educated people lived in cities, without cars, and the jobs they would be able to get were in the suburbs, requiring either a car they didn't have or a nightmarish public transit commute to places with horrible public transit.(It was more complicated than this, of course, with enforced residential segregation and other types of racial discrimination having a large impact on location patterns).
As poverty moves to the suburbs, people are going to be in worst-of-both-worlds territory. They'll need a car for jobs, and for everything else, and cars are expensive things. And while there is no secret welfare system, it is the case that there are often more readily available social services and similar support systems - private and public - in some urban areas.