As somebody w/ Celiac, you'd be surprised. Many a time I've been poisoned by normal gluten free things being tainted by poor manufacturing lines, or companies mixing in other product. Tortilla chips with gluten, Hashbrowns/Potatoes coated with wheat flour, so many things are made not-gluten-free for no reason.

There is always a reason and it usually has something to do with money. We really need to find a cure for Celiac 'cuz wheat is just too ingrained in our culture to be removed. (pun not intended, but also not removed so...)