I wonder if teachers are aware of the lasting psychological damage they are doing their pupils. They probably are, and that is the real reason they are teachers despite the starvation wages they get for endless work.
Hanlon's razor fits here. They don't need to be malicious, just stupid. Public education is a dumpster fire for many reasons, the not least of which is due to the quality of prospective educators. Anyone with a brain can earn more money or do more "good" elsewhere.
It's also not only scraping the bottom of the barrel as far as intelligence and erudition, but then a strong iterative selection against those intolerant to anonymous bureaucracy and in favor of obliviousness. You end up with natural corrections officers by default, albeit with smiles and colorful pictures. For you, it was formative; for them, it was Tuesday.