There are people who do not want to eat foods with genetically engineered organisms under any circumstances if they can help it.
There are people who just want to know if genetically modified organisms are in the products they are eating and feeding to their families.
Ultimately, the people who do not want to consume GMOs deserve as much consideration as vegetarians who don't want to eat meat, people whose religion provides specific dietary restrictions, or people with food sensitivities and allergies who need to stay away from specific ingredients. We all have a right to know what we are buying, and to choose whether to buy it. Joe Rogoff (president, Whole Foods Market, Pacific Northwest Region) says it "is about transparency and the consumer's right to make informed decisions."
They can argue that there is a cost in labeling, but food manufacturers change labels frequently. David Byrne, former European commissioner for Health and Consumer Protection of the European Parliament, stated that when Europe introduced GMO labeling in 1997 it did not increase costs.