... except for the year I spent in overseas where it was simply considered basic "maths" and fully integrated with the science curriculum.
I quit high school for college. I don't believe my "gifted" high school classmates were served well by their senior year high school calculus experience. It was largely a waste of time, a "droning exercise in abstractions." In college I saw calculus had practical applications in other classes, which is the only reason it mattered to me. That wouldn't have been the case in high school.
My wife, who is a very practical person, saw that she could skip high school calculus by taking both calculus and statistics in college while finishing high school, and do it in half the time. As a college student she later tutored others in both subjects and has occasionally taught medical statistics since then.
I have a niece, my brother's daughter, who is similarly comfortable with math. She skipped the typical U.S.A. high school calculus experience too.
Algebra, calculus, and statistics are all subjects our schools could be laying a solid foundation for as early as the third grade, and explicitly so. There's no reason every kid coming out of elementary school shouldn't know at least what they are.
Innumeracy and scientific illiteracy are serious problems in the U.S.A..