Even the concept of food being “authentic” or “inauthentic” is pretty dumb. Pretty much every food short of raw foraged ingredients is the result of cultural exchange.
You could argue that an Italian cooking with chilis or tomatoes is inauthentic and that the resulting food is more Mexican than it is Italian.
Extending the concept from ingredients to techniques, you could argue that every food that relies on the cold chain (refrigerated/frozen storage and transportation) is an American food because the cold chain was created by an American.



I dont think most Mexican food in the US is tex-mex. Fast food like taco bell isnt tex-mex, and most taco trucks and takeout places aren’t. The main category of restaurant that seems to be largely tex-mex are sit-down places with names like “El Mariachi” that cater to non-hispanic people and advertise the cheapness of their margaritas.