OK, I'm going to speak of my own experiences here, back in the late 80's (so dated, but still interesting)
When I was in 8th grade my family moved from New Jersey (which then and now has one of the best public school systems in the country) to Arizona (where public schools, to put it bluntly, suck donkey balls).
In New Jersey, in 8th Grade, every single student was expected to be taking pre-algebra, with advanced students taking full up algebra mixed with geometry. Calculators were banned, all work had to be done by hand and we had been required since 5th grade to show all of our work by hand.
In Arizona in 8th grade, in the advanced math class, they were just then (second semester of 8th grade) starting on... adding and subtracting fractions. And students were required to use calculators to do this. We had been doing this in NJ in *5th* Grade, by hand, and when I proceeded to breeze through the in-class assignment without touching the calculator the teacher pointedly placed on my desk I was yelled at by the teacher for not using the calculator, she wouldn't even look at the answers because I 'did it wrong' by not using the calculator.
In New Jersey, in 8th Grade, every single student was required for our English class to turn in a 5 page paper on the book we were reading *that week* every week, the paper had to be typed, and we were expected to properly reference the book in question in MLA format. And these were *not* young adult books. The weekly readings were from an anthology of short stories that included works from multiple famous and influential authors. For each quarter we were assigned a 'major work', in the first semester of 8th grade we read Moby Dick and The Red Badge of Courage. I'll note that 7th grade we did Shakespeare's plays.
In Arizona, in 8th Grade, the *advanced* English class was... reading a young adult book I've completely forgotten about for the entire semester, with a single 8 page paper due at the end of the semester. In between we spent most of our time watching movies in class (mostly movie versions of Broadway plays) and 'discussing' them, with no written work required.
In New Jersey, in 8th Grade, the History class I was in was engaged in an in-depth study of the causes, battles, and consequences of the Civil War during the first semester. If I'd stayed there the 2nd semester would have been an equally in depth study of the labor movement in the 19th and early 20th centuries. In 7th grade we'd studied the Revolutionary War, including field trips to the historical monument in Morristown and an extended field trip to Valley Forge.
In Arizona, in 8th Grade, the instructor had us reading from a woefully inadequate history text that had been published in the 1960s, was riddled with blatant errors, and was utterly boring and inadequate. In my first class there, the 'teacher' noticed me shaking my head at some of the inanities and decided to 'put the new kid in his place' and sneered that if I thought I knew better that I should stand up and give the lecture. Considering that in NJ that was a regular thing for all students, being required to study a topic and give in-class presentations for entire periods, I stood up and gave the same one I'd given just a few months before. He was *not* amused and I got detention for that one.
In short, in New Jersey, students were challenged to rise to the expectations given them and pushed into doing so, in Arizona the expectations were lowest-common-denominator and the teachers couldn't be bothered to actually, you know, teach. In New Jersey they started with the assumption that the kids would learn and were perfectly capable of doing the work. In Arizona they started with the assumption that the kids were dumbshits who couldn't be bothered to learn and just had to be kept entertained.
Lately in AZ we've had campaign after campaign for ballot propositions to raise funding for schools. Tax increase after tax increase, to increase the amount of money spent in the classrooms to improve our schools.
After 5 rounds of this farce? The raw 'per student' numbers are way up, but almost none of the money is in the classroom, 90%+ of it is diverted to administrators, infrastructure, and 'programs', generally 'diversity' programs. None of it is spent on actual teachers or students, and they keep on coming back for more.
And they still bring students into school with the expectation that they don't want to learn and can't learn and must never be challenged to learn.
And thus generation after generation fails.