You seem to be making the assumption that English is as popular and widely used as C. I would like to remind you that it is only the case in western parts of the world, which is by far, not the majority.
What proportion of developers can write C at an analogous level to first, second or foreign language? 20% seems like quite a good ball park estimate, from my (anecdotal) experience.
Nor sayng it's perfect and universal, but it is pretty widespread even outside "The West"
IME, Indians and Germans who use English are generally extremely proficient in it.