True, there is no "official" language in the US, but the majority of us do speak English. There is a large percentage that speak no other language. American English has been the accepted language of communication in general and until recent years was the only language taught as a required subject. To do business and be able to communicate here, it is more likely that you will gain more by using English over any other language. True there are some isolated areas where other languages are used, but most that do so also know English or have a working knowledge of it.
I work for a customer who has a large Hispanic work force. There is one of them that translates for the workers and he takes advantage of the language barrier for his own personal gain. Businesses that are local and have no need for a Spanish speaking person, especially one who knows no English are not likely to advance that worker because of the language barrier. The lack of a working knowledge of the language that the majority uses only hampers their chances for better jobs and other opportunities. If you move to Mexico in an area where English is not spoken, why would you expect them to change their language just for you, especially if you entered illegally?
If you expect to advance and find the better jobs, you learn the language that is spoken in the country by the majority of the population, otherwise live a lesser existence than would be possible in you knew their language. Other than to provide an convenience to our visitors, we have no need to speak their language.