My other half is a teacher, a good one too. He is always marking planning and works late doing after school additional lessons. Since leaving the local comprehensive he joined a private school in September. He has been told on a few occasions by parents that they "pay his salary". His view is that he would rather go back to the comp and deal with difficult children who can change, but are initially the way they are due to challenging home environments. He said nothing can be done to solve the problem of difficult parents. He has had parents scream at him because their dc was moved down one set. His words were "they do more damage by pushing us constantly, it's tiring, degrading and when that happens I feel worthless. I struggle to put together a decent lesson after things like this happen."
He also felt that parents in the comp respected teachers but in the private school they see it as customer service where they buy the product.
I have a dd who I put through a private school, I let the school make the decisions with what group she would be in, I never interfered.
I struggle to empathasise with those, who I am sure are on here too, think they know their child's ability in the subject better than the professionals.
My other half is now thinking of resigning, but feels guilty knowing the school as do many other schools, struggle to find maths teachers.
Leave the teachers alone folks. Let them do what they need to.