So there are families that can trace themselves to Mexican California, but I believe their numbers and culinary influence was overshadowed by the significantly bigger population that came later. But maybe that’s just as authentic. They were bringing and making dishes, not copying them.
And there's two parts to this: first one is that there's not much diversity. Vampiros and flautas are, more or less, tacos. It's almost always the same proteins, same pinto beans, etc. Come to think of it, I can find cochinia pibil in the Mission… at a restaurant that specializes in Oaxacan food. They've got mole (one kind), which is amusing considering that Oaxaca is a state known for it's diverse variety of moles. Anyways, back to arguing about whether SF tacos and burritos are authentic.
The second part is that Mexican food (more than other Central/South American cuisines) is seen as peasant food. You get it from a truck or a taqueria. Occasionally from some place with table service. I can think of two sorta fancy Mexican restaurants (one, if not both, have since closed). Ceviche? Well, I can get that at the Mexican grocery store or the fancy sit down Peruvian cevicheria.
The Bay Area serves up a comically thin slice of Mexican food, even compared to other parts of California or the US.
But Tacos, not burritos. Burritos are their own thing in the bay area so they cater to the local taste.
If you haven’t yet, check out Al Carajo, Loltun, El Patron, Tacos del Barrio (who do al pastor on a proper trompo), and El Charro (a little, probably unpermitted stand on the sidewalk at 18th & Mission who somehow also have a trompo set up for al pastor).
Exception: Best SF Mexican tacos is of course Taqueria Vallarta in the Mission.