It's legacy of a of hardcore state-backed rationalist ideology of thr USSR.

Soviet doctrine treated Marxism as an objective, scientific law (I believe that's partially how the ruling class enforced to legitimize its power). Combined with post-WWII competition in space and computing, this mindset institutionalized rigorous STEM education, creating a massive pipeline of uncompromising textbooks, teachers, mathematicians, and engineers.

This partially explains why egineers from former-ussr places are good. They are taught by those and with materials which were produced by above mentioned processes.