All the inspectors have to do is watch them make it and test the ingredients.
Unfortunately, the government is moving more and more toward allowing the industry to inspect and police itself. Even though the legislation providing for government inspectors is still in place, massive defunding has made it all but impossible to follow their mandate. So what it boils down to is the beef industry saying "trust us". And we've seen in California, and now in Washington, what happens when the people start demanding the labeling of food.
That's just stupid! How can Toco Bell NOT prove that their tocos contain beef? What else could they contain -- kangaroos or horsemeat? All the inspectors have to do is watch them make it and test the ingredients.
exactly the same idiocy as the urban legend that KFC changed its name to KFC from Kentucky Fried Chicken because "they don't actually serve chicken and are thus not allowed to use the word in their advertising", which is utterly bogus as they never changed their name, and use the word chicken liberally in all their marketing (including their own website).