Do all these people also speak some English?

(I live in NYC where the mix of languages is thick, but I rarely have to reach even for my Spanish, because English is still commonly understood everywhere, at least to some degree.)

Not all of them, no. Where I am (California) there are a lot of monolingual or barely functional in English speakers of Spanish and Mandarin. Also where I live specifically, Vietnamese and Cambodian. Those are all seniors though.

In Chinatown on Manhattan, there are areas like that (though I suppose the senior citizens mostly speak Cantonese there). Many of the store signboards are in Chinese only, and inside, the labels may also be only in Chinese; then only the fact that I still remember a bunch of kanji allows me to tell a duck from a chicken, when both are wrapped in impenetrable dark plastic.

Yeah I know the area. My wife and I have been through there a few times (she is from Taiwan). Lots of people who barely speak any English at all, but you might not know if you didn’t speak Chinese.

That kindly old man making noodles behind the counter on that restaurant you frequent off Canal St? The one that always has a stoic face and never says a word? He doesn’t speak any English, but try chatting with him in Mandarin and he’ll talk your ear off with his life story.

I have personally been to places in NYC (and surrounding areas like Newark) where the staff does not speak any English at all.

The area I and in mind the answer is yes. But there are areas where it would be no. I’m in the Deep South.