One pressure to promote has to come from the desire to pass the little hellions on to the next grade so the teacher doesn’t have to deal with them two years in a row.
The teachers are badly trained, the textbooks are badly written, and the lessons are painfully boring. That’s a recipe for failure.
Unbelievable!
This has been going on for 50 years or more. It’s just that each generation finds it can learn less and less, and still get good grades.