In high school I was national laureate of Physics Olympiad. Then I went to college with a mindset that I can learn anything. First week's physics lecture taught me that, no, I can't, if the teacher's attempt at teaching is so abysmal. On the final exam at the end of the semester I ended up with barely passing grade, that I had to fight for at additional verbal exam. The same semester I got top grade with informal plus for excellence in the physics exercise classes where we solved physics problems, because the person teaching those was not terrible at his job.
You pay teachers garbage pay and not evaluate them competitively so you are attracting a lot of not so great people to the profession. Then you just give them students they can't control, let alone teach and never monitor if they actually learn anything during classes. So that's what you get in the end. People who haven't been taught anything but still "passed".
Wanna have educated young adults? Do Finland.