It's odd that teaching unions get so much hate in the USA when there are way more objectional forms of public sector unionism (I don't just mean 'hur dur police unions' either).
If your kid is a disaster it is a lot easier and acceptable to blame teachers than yourself or "hur dur police unions".
And politicians aren't going to tell their constituents they are terrible parents. Just like they won't tell them they are fat and lazy. No we will blame doctors, hospitals, insurance companies and pharmaceutical companies.
It is actually pretty amazing how much of our individual medical costs we have direct control over. Instead of eating right and getting a little exercise we will eat ourselves into a coma and then expect everyone else to pay money to fix us.