Problems in educating young children often begin with the family at home, who don't care, won't participate in discipline, and raise a hue and cry every time a teacher wants a better life for the child.
Children aren’t a blank slate when they get into school. Genetics, parenting, and culture all have an effect.
That said, the fact that teachers that make tenure basically can’t get fired for lack of performance is ridiculous. Imagine if you just had to be a good little coder for a few years, and after that as long as you put any amount of effort in at all you wouldn’t lose your job.
I certainly had teachers growing up that were terrible at their jobs. I also had some that were pretty good. Most were mediocre to the point where I don’t think they’d stay employed in a regular non-union type job. At the very least they wouldn’t be getting performance raises.
the fact that teachers that make tenure basically can’t get fired for lack of performance is ridiculous
Had a friend who worked in one of the worst performing public schools in our city. According to him the main problem was that you simply couldn't keep good teachers no matter what you offered. Half the new teachers they hired didn't make it past the first year. Had they started firing teachers who underperformed on top of that they wouldn't have enough teachers left to keep the doors open.
edit: not disagreeing with the idea that tenure for teachers is a bad idea, just that I don't think that is the primary problem in these worst cases.