I also believe a very big problem in education is that most teachers can’t teach math or science beyond sixth grade or so; the union rules requires a math teacher to receive the same pay as a gym teacher, so those that can DON’T teach - they work in the private sector instead (where supply & demand reaps richer rewards).
For years we’ve heard that “education” majors are at the bottom of their college classes; I can absolutely believe it.
A pet peeve of mine is that in the best of circumstances - i.e., America in 1950 - people do not select themselves to be grade-school teachers because they love mathematics. They select themselves to be grade school teachers because they like to deal with kids. The result is that grade school teachers tend very strongly to think of mathematics in terms of Arithmetic - specifically, number crunching.
Word problems were the bane of the typical student; they were candy to me. An interesting challenge. But I did not on that account become convinced that I was good at math. I got no particular encouragement, and I disliked the number crunching exercises so I was not in love with grade-school math. That came later, in Plane Geometry class.