In most cases, the schools are the parents! Ask any teacher about their success at contacting the parents of the students.
In my inner-city middle school (boys only), I taught over a hundred kids. Do you know how many parent-teacher conferences I had where either one of the parents showed up or even the biological parents? I think the number was about 5 over three years and in one case I taught two of the boys for two years. I spoke most often to aunts, uncles and grandparents. I had students where I could not communicate with the parents or even the student himself because Catholic Charities saved these families from the mountains of Burma where they spoke a language unknown to the outside world. We had no translators, nor could we find anyone who would serve as one. How well did that kid do compared to your private school student?
You would really have liked on of my major discipline problems. He was a young refugee from Liberia. Despite their country speaking English, his mother was barely literate. Then we found out the reason for his refugee status. This kid's father was the leader of a Marxist rebel army attempting to overthrow the democratically elected government. That kid wound up being the reason I left the school.
That is the reality in those schools.