Language is a complicated and very fluid social construct. What means one thing somewhere might mean something different somewhere else, even if the same language is spoken in both places. Both usages of the word are correct, and it's both the responsibility of to the speaker and listener to understand each other. It's confusing, but that's how things are in the real world. Of course you can say "America" to refer to the continents, and if that's what's dictated by social contract where you're from, then more power to you. I'm just saying that you can't judge an entire nation of people based off the colloquial usage of a word (not that you were, I'm referring to the person I responded to).