Call for a pizza here and use Spanish and your order will be taken. Pretty much the same at any fast food restaurant ... indeed at just about any restaurant.
There - right there - is another indication that this is more of a settlement (or resettlement) of this country by Mexico than just immigration, if the natives have to speak their language in order to communicate in their own country.
Considering that most of the western part of the USA was originally Mexican territory...it stands to reason that maybe Spanish should stay as one of the languages spoken.
And...why are you so fearful of a bunch of Spanish-speaking brown people? Is it because they come here, work like dogs, start businesses, make money, pay taxes and generally within 2 or 3 generations become successful? Here where I live, most of the car washing services, smaller restaurants, mini-marts, painting and construction contractors are Latino-owned and operated businesses. My downstairs neighbor owns a car repair company and he does mobile repairs too. His children are bilingual, they're all in school. They live pretty cheaply (I know what their rent is) and he supports not only his family, but his sister's family, his parents and family in Mexico.
If you want the Latinos out of the country, then go do the jobs they do...landscaping, farm work, construction. Wasn't it in Georgia they tried to get white folks out to harvest and none of them lasted an entire day? Truth is, you can fuss all you want but we, here in the US, NEED these people.
Never heard of it, and I'm going to ignore post seventy because it's race-baiting and offensive and the country survived quite well without all these people taking jobs under the table and living twelve to a house.
To the OP topic, why should they bother to learn a difficult language when they have bilingual education available on our dime and fifty badzillion cable channels in Spanish? Even the DNC last year had an interpreter for them. You'd think if they were so hard-working and wonderful, the Mexican president would call them back like he promised to if Trump was elected.
You come and talk to them. I live right on the border, remember? 90% of the illegals here in Hidalgo County are from Mexico and come here because they have friends or family living in this area.
Before moving here in 2012 I lived in San Diego for 35 years, only 9 miles from the border. 90% of the Hispanic illegals in San Diego country are from, yep, that's right! Mexico!