Except it's not just a cash flow problem, it's first and foremost a community collapse problem. Poor immigrants buy in bulk and share all the time. Eventually the only way to avoid poverty is effectively cooperating with other people - at work to accomplish tasks worth paying for, social networking to get a job, staying married to provide for children. I am not patronizing anyone here, just acknowledging that their troubles have many more dimensions than just unit prices of small portions of various goods.