In many parts of Europe, they actually do: if you study maths or even something related like CS or physics, you'll basically see proofs from day one. The split

In many parts of Europe, they actually do: if you study maths or even something related like CS or physics, you'll basically see proofs from day one. The split between "calculus" (non-rigorous) and "analysis" (with proper proofs) seems to be mostly a US thing.