While this is true, I would like to point out a good portion of schools do allow students to continue to more advanced math if they elect to.

I went to high school in California, I was able to take all the way up to what was called Calculus BC, which covered up to learning integration techniques. This was in a bay area high school that was underfunded, and the majority of our senior class didn't graduate.

But the vast majority of students stop at Algebra 2, and struggle through it.