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.

Some brands use wheat to make the chips more crunchy. Just like IHOP puts wheat in their scrambled eggs. McDonald's uses wheat in their french fries. They stick wheat everywhere.

There are tortilla chips that do contain gluten, or are cross-contaminated with it. A gluten-free label means they guarantee <20ppm gluten in the product. That’s useful info!