I don't know what culture you're from, but it is considered rude here not to speak the language of the majority. If you're out in public, you are expected to speak English. If you are in Quebec, you are expected to speak French. If you go to a German settlement colony, you are expected to speak in German or a language close to it like Dutch.
Say what?? I've been to Turkey, and I do not speak their language, I sit with a friend of mine who is from Turkey, we spoke in English, it was just me and him having a conversation, why do I must speak their language when I'm talking to one person? If my friend understands me, and I understand him, then why is it rude not to speak their language when I'm not even talking to anyone else but him. It just doesn't even make no sense.
I've seen Chinese people speak Chinese when I ordered food from a Chinese restaurant in America, and I don't even consider that rude, because they're not talking to me, they're talking to each others. It'll be rude if they spoke in Chinese to me, when I don't even know their language.
You know that the United States has no declared official language, we have many immigrants here with non-English languages, and they are not required to know English, but they should know some.
How so? You don't know anyone else there only the person you are talking to. Since when are you not allow to talk to one person when you are at a place where a majority of people there share the same language? There's no law against that. It's a public place, a free world, you can go anywhere to have a private conversation with anyone.Also here, what you say or do is open to EVERYONE. There is no such thing as privacy unless you go to a private place.