Pretty much everyone except people from “America”, that is, the US.
Well that is a broad generalization spoken from a place of ignorance. I promise you that the vast majority of Americans (that is, people from the U.S.) know about the Americas (that is, the continents).
That being said, colloquially, the term “America” generally refers to the United States. And that’s true most everywhere, not just in the U.S.
Most people will say “North”, “South”, or “Americas” (plural) when talking about the continents.