We started blaming parents long, long ago and never stopped. Unfortunately that's not effective in many cases. A lot of parents are ineffectual, apathetic, or shameless. Blaming them might make the rest of us feel morally superior but it doesn't improve outcomes for their children.

And for older children, peers tend to influence them more than parents anyway. Turning around a failing student will often require separating them from their current friends. Tough to do when you can't afford to move to a better school district.