Kudos to Gary T and to Fish for their answers.
In The United States we talk a lot about letting something called “the market” decide things–except, that is, when the market does decide things and we don’t like what it decided. Interestingly, when people call for regulation to abolish what people have decided collectively to do, people often resort to talk about “tradition” and “values”–the same sort of rhetoric which is used to support the market when it gives results which aren’t found objectionable.
When a bank–or whoever–chooses to use another language than English, or a language in addition to English, that is a market-driven decision. They do so because they are facing facts as to how conditions are.
Yes, people who are not native speakers of English have been coming to this country for centuries and yes, such people often received little or no accomodation in the past. The result was enclaves of people who did not interact effectively with the population at large. As I understand it, there are still a fair number of people in New York and Chicago who speak fluent Polish or Russian but who cannot deal effectively in English. When I was attending a Catholic high school in St. Louis, I had Italian classmates whose parents spoke a kind of Chico Marx-style parody of English, and that with difficulty.
In earlier times the phenomenon was much more pronounced. In the late 19th Century, it is said, there were large parts of St. Louis where it was much less common to hear English spoken than German. The ACLU had its origin in a case founder Roger Baldwin took during World War I; a man in St. Louis was walking down the street when he saw his father sitting on the front porch, and he said good morning to him. A policeman overheard and arrested him. The man’s father was a German immigrant and he had addressed him in his accustomed tongue at a time when speaking German in public was illegal. One may not have been able to find bank signs in Spanish in those days, but you may be assured there were many signs around town-- as well as newspapers, magazines, etc.–in German.
As society has become increasingly complex and mobile, the pressure to assimilate and learn English has increased, as has the opportunity. At the same time, however, the pressure has also grown for governments and businesses to accomodate non-speakers while they are learning English, and not just in isolated neighborhoods.
Why does this upset people? Mostly, I expect, it is a matter of whose ox is being gored. The in-laws of a friend of mine complain bitterly that their old parish in South St. Louis currently offers Masses in Vietnamese. When they were growing up in the neighborhood, the same church held services in Polish, but somehow that was different. They, needless to say, are of Polish extraction.