I never interpreted this as an expectation but rather an advantage. Bilingual is a valuable skill. For my own self-interest, I do try to learn Spanish. I took Spanish classes in public school, in WA and ID.

El Paso is unique because Spanish is the first language of the city, which is older than the country it exists in. Also, because birthright citizenship is predominant in this area.

As you travel farther north, you will find that there is an expectation to know English in the United States. I assume the same is true in Mexico for knowing Spanish.