it’s an insult to everybody whose last name ends in “ez” to think that they are incapable of doing things legally and aboveboard. as if they are incapable of following the same rules that everyone else must.
Here is Silicon Valley there is no shortage of Mexicans/Central Americans who will be happy to teach you a word or two of Spanish, I've managed to pick up enough so that I could struggle through being dropped anywhere south of Tijuana.
OTOH, a Vietnamese simply will not teach you a word of Vietnamese. They insist on learning English (or Spanish) and speaking it as best they can whenever dealing with non-Vietnamese.