[khazhoux]

This is your misperception.

In the instances where a person says "English" in this kind of context, it catches your attention and you infer that the person is an English-speaker, and possibly American.

But when a person uses the generic word "language", you don't notice it.

This leads you to believe that English speakers "tend to use the word English," when that's not the case necessarily.

I don't know what this perceptual fallacy is called, but there's probably a word. In English :-)