Labeling sounds simple until you consider all the things that will have to be done down the road from the product arriving on the shelf.  Farmers who grow genetically engineered foods also grow non-GMO foods.  They harvest these foods at different times of the year and use the same equipment and storage silos.  In order to keep GMOs separate from non-GMOs they will have to build new silos at a cost of about $500,000 each.  They will have to clean equipment more often.  Trucks that pick these crops up will be washed more often as they take them to storage in new expensive buildings at the grainery, whose equiupment will have to be washed more often.  These expensive steps will drive up the costs of all products more than the printing of a label, because you have the right to know that your food contains ingredients Nobel Prize winners say are safe.  How much sense does that make?