Not just that, but in a world where (particularly for poor and immigrant communities) employment is frequently informal and based on social and family networks

Not just that, but in a world where (particularly for poor and immigrant communities) employment is frequently informal and based on social and family networks ("The restaurant my cousin works at is hiring" or "My brother's construction gig needs some extra hands on Friday"), moving to another city means giving up a huge portion of your social capital and possibly all of your earning potential, as well as your (similarly informal) safety net.