From what my high school math teacher told me, it's because the modern U.S. curriculum was last drastically revamped in wartime to pump out future engineers and physicists, which is why there is so much emphasis on trigonometry and calculus rather than sets, logic, statistics, or discrete math.

Are you talking about the school algebra that for most students precedes differential and integral calculus, or are you talking about the abstract algebra that in most curricula follows calculus as an upper-division undergraduate course?

Yes. The latter. However we had Analysis (Calculus) and Lineare Algebra at the same time. Algebra came afterwards.

Calculus in school was as boring as everything else. School math is mostly a basic version of engineer's math.