In Spanish, they call it fútbol, rather than football, and in Chinese, I think it is pronounced something like Zúqiú. Most Southeastern Asian countries don't call it football or a variation thereof. Australians and parts of the British isles call it soccer I believe as well.
Things are named and pronounced differently in different languages.
The fact is, "football" was already taken in the American vocabulary by the time soccer rose to popularity in the US.