Finland is an excellent model but it required weeding out bad teachers who couldn’t do better in the classroom or who couldn’t handle more difficult education and certification. This will never broadly happen in the US.
It’s easy to point the finger at unions- mostly because it is a narrative that has been pushed hard for years.
The issues are way larger than the person in front of the classroom. Bad teachers don’t help but thinking I can just take test data at the end of the year and figure out which teachers are bad is wildly useless
The US in many places is still arguing endlessly about Charter schools and homeschooling to allow 'teaching' the most woo-woo nonsense, and offer endless bloviating about testing batteries but nothing about curriculum/pedagogy requirements. Textbook publishers cater to opposing markets (California and Texas) and its just as adversarial as every other element of US society these days.