Can undergraduate math courses be taught at a high school level? [closed]

In Spain, some linear algebra is taught in high school and is examined on the exams required to enter the university. Topics taught include matrices, determinants, solvability of and solving linear systems of equations, and Euclidean geometry of lines and planes in the plane and three space. Basic probability is also taught, focusing on the binomial and normal distributions. One variable calculus is taught in more detail, and notions such as continuity and differentiability are included.

One might ask how much students really learn. The answer is that most of this material has to be retaught, albeit rapidly, in the first few weeks of the university.

In the US, with the great flexibility of its otherwise generally undemanding school system, advanced students often find a way to learn multivariable calculus, linear algebra, and more. The limiting factor is often the availability of an instructor competent to teach these things.