Chances are, if you're eating anything with one or more of those ingredients, it's Tex-Mex. Beef was the meat of choice for Texan ranchers back in the day, but it's hardly used in Mexican cuisine outside of the extreme Northern reaches of the country.
Cumin was imported to the US and England from India, and, while it's been slowly incorporated into dishes in Mexico, the US was quicker to adopt it as a spice. And let's face it -- gringos love wheat, and pretty much any burrito you'll find up here is wrapped in a wheat tortilla rather than the maize-based tortillas down South. A general rule is that the more starch there is, the more Tex-Mex it is (with the notable exception of tortas).