I knew a woman who worked in Head Start giving aptitude tests to pre-schoolers chosen by the system for special attention because they were in a welfare family or whatever.
Every so often she’d see one of them a few years later; as it was a small town she had some idea how they were doing in school (usually not that well). There were many times where she just shook her head and wondered if their time in Head Start had helped them at all.
This was thirty years ago, FWIW.
Probably not the fault of Head Start. It is more likely the grinding negativity of the public school system. It’s little more than a warehouse in the ‘poorer’ school districts.