I think you'd need stronger evidence than has ever been given that raising minimum wage concurrently raises purchasing power, _especially_ for staples. In the end, it's a feel-good solution - politically, it's hard to pass up, as a great deal of people would be very happy about seeing their paycheck get bigger, without also examining whether the prices around them are going up as well, or noticing that their coworker cohorts are thinning out.