Go to a taco truck anywhere in Mexico and USA and your tacos will be on corn tortillas. In Mexico corn tortillas are sold daily at tortillerias by the kilo....locals bring their own towel or bag daily.
You mention the border and yes Tex-Mex uses flour tortillas for burritos, etc. but traditional taco, enchilada, tortas all lard free corn tortillas (water, corn, lime).
Flour tortilla “bowls” for taco salads are an abomination to Mexican cuisine