Look, there’s half a billion of us and I’m not gonna reject the possibility that wherever you’re from people say “café negro” for some reason, but yeah, no,

Go to Google Maps and search for the phrase: “Cafe Negro Mexico”
There are several cafes named that and if you search South America there are some there too.
Here’s one in Mexico City:

Most Spanish speaking people are Mexican.

We’re all on the internet. Why make things up when people (including yourself) can fact check?

Spanish Speakers: Native: 500 million - Total: 600 million

México - population of almost 130 million