[kennywinker]

There are plenty of foods that have never had gluten-containing ingredients, but have always been made in factories or contexts where they come into contact with gluten. Celiacs, and people with NCGS who have strong reactions, when given the option will usually avoid anything that hasn't been actively tested and confirmed gluten free. For things like a bag of rice, or produce, there isn't an option with that label for re-assurance, and then it's a gamble... the odds of a bag of rice containing gluten may be low, but with such big consequences it's still a gamble. So the proliferation of the GF label is useful. There have also been a ton of new products launched that are gluten free, so it's definitely not just a labeling thing.