My wife works in a low income school, largest and poorest in the area (a relatively large city.) Pumping more money in does not help. More after school problems does not help much. As far as academic achievement is concerned, these kids are completely stuck because they have what we would consider terrible situations at home.
Sometimes the parents just don't care, sometimes they just don't have the time (multiple jobs). More often than not there is only one parent at home. There's only so much a teacher/school can do if the parent is picking up the ball when the kid gets home.