There are a couple of towns in my area where virtually NO ONE speaks any English.
And it's not that they are bi-lingual but choose to converse in Spanish, they simply don't speak English at all. And as you alluded to, they are in a position where they don't really need to learn English to survive. These towns become enclaves where they isolate themselves from the outside world.
EDIT: to purelife, yup. And I don't have the slightest problem with hiring immigrants as long as they can do the job they're hired for, but customer service requires the ability to communicate, hay??