Not just afford - often time those suburbs specifically barred non-whites from owning property. Additionally red-lining and racist loan practices forced that wealth gap to grow.

But I think that's separate from the car issue, mostly. Originally satellite communities had commercial services - local shops and the like. But those were phased out due to a lack of demand, I think due to societal shifts that were egged on by marketing "cool kids have cars" - and the like.