"DIS IS 'MURICUH, U GODDA SPEEK INGLISH HEER!!!11!1!!" *dueling banjos*.
This is linguicism. Insulting someone's language, especially when it's a minority language in a certain location, is almost like insulting their skin color.
I can understand wanting to be spoken to in a language you're familiar with, so do I. But when you're running a place with a half-Hispanic population, you're expected to know some damn Spanish.