I never said there wasn't regional variety. I said I'm probably expecting something from Southern Mexico when I eat Mexican. Either way, Tex-Mex isn't really "Mexican", it's definitely a fusion, so if you are expecting Mexican food you'd be surprised.
Texas was one of those regions. So was California. The borders moved. The Tejanos are still here. All border areas have mixed styles and ingredients. "Fusion" implies someone intentionally looked at two disparate cuisines and mixed them on purpose.
