I suspect that the food manufacturers say, "OK, if we make it without wheat then it's gluten-free." Which is not the case. I've seen things so labeled that contained oats and/or barley, which are every bit as dangerous as wheat.

And it's astonishing how many people don't make the connection between flour in a food item and the fact that it's made of wheat. The good side is that restaurants chefs and servers almost always are helpful, understanding and will go out of their way to prepare something in an uncontaminated pan.