What makes you think there are no other ingredients added? McDonald’s does their best to make sure that everything tastes exactly the same at every location. I don’t think that could be done without some kind of engineering to the beef. Now whether that’s before or after it’s slaughtered (or both) I do not know. Plus there are different grades of beef and as Michael Hoffman pointed out differnt cuts that can be ground into hamburger. So as far as I can tell, the only similarity between McDOnald’s and the "upscale" places is that they are both beef. But that would be like saying that there’s no difference between a meal at a Ponderosa and the Hereford House in Kansas City because they both serve steak.