I'll add that not all parents are prepared to come out and support their own children.
We had parents who switched off their phones as soon as their children got through the school gate, just so that we couldn't disturb them by getting in contact.
We had one ASD diagnosed pupil who was deliberately violent towards staff. Believe, me these weren't meltdowns - it was calculated. He knew exactly what he was doing. I've worked with ASD pupils for 40 yrs. This pupil is the only example I can think of where an ASD pupil was deliberately violent. He was playing the system.
For the sake of the other pupils, we had to organise for him to work in a separate room with more than one member of staff there. This usually meant that a TA or teacher would be assigned to the pupil for the period, at the same time as another member of staff was having their "non-contact time" there.
The Ed Psych assigned to us was worse than useless.
We asked the mother to come in and work with us on temporary basis. Her tactic was to sit through the meeting, smile, say nothing, agree to nothing - and then leave.
I understand that many parents of "difficult" children see school as respite for the parents. However, it's even harder for a classroom teacher to work with such a child, since the teacher is typically working with the child plus 30 others.
In the end, our LA agreed that the pupil I mentioned above could move to a larger school where staff were pulled away from other pupils to work with him. Minimal compliance was rewarded with chocolate. He got what he wanted - he never had to set foot in a regular class again.
That might sound like a win, but his "support" took away from children who probably needed it more.