At a guess, and this is based upon first-hand experiences in Silicon Valley over many years, the illegals consider this part of the country actually a part of Mehico del Norte, and sneer at any suggestions that they need to learn English at all.
After all, why would they need to? Barky already mandates that even his signature website is translated to over 150 languages by his own admission!
The US is 61?
That reminds me. I need some beginner lessons for Mandarin, showing phonetic pronounciation and emphasis. Symbols I can learn later. Be Prepared is my motto.