It's money, and it's not. There is basically a viscious circle. There is no denying that the best public schools are in the most affluent communities, or at least communities that are economically stable. Good schools attract the people who can afford to live in that kind of community. Those people are more likely than not well educated, so they value education already but more importantly, have the resources to be able to commit themselves to their children's education. These are parents who will read to their babies, surround them with stimulating, educational toys and books, send them to pre-schools and day care centers that will help ready them for school, and have the means to provide basics like healthcare and nourishing food for growing bodies and minds. These are kids who have seasonally appropriate clothing, are generally in good health, get a good night's sleep in a fairly peaceful home, go home to a parent or spend their afternoon at a quality after-school program, have a quiet place and supplies to do homework and ample opportunity to pursue sports and other activities in safe, age-appropriate settings. Parents who have the kinds of jobs that allow them to take a sick day if needed, or take the morning off to go to the school play or science fair, and the skills to run a fund raiser or be the treasurer of an ample PTA budget that raises enough money for all of the extras that the school budget doesn't cover, such as enrichment programs, family activities, extra games and learning aids for the classroom, library books and all of those other things that further connect schools and homes and make schools a better place. Not to mention, good school districts attract and retain good teachers and administrators who want to set down roots and stay. This is what life is like in my town.
Contrast that to life in the city next to mine, where the low-income rate is over 70% (in my town it's under 10%). These are families where just making ends meet is a huge concern. Where many parents are themselves uneducated, young, poor, and single. Where working requires multiple part-time, low-wage jobs without paid time off, where transportation is largely public, and families have to scramble for childcare before and after school, relying on city-run programs that are of poor quality. This is a city where many of the children who have outerwear for winter receive it from a charity and where sports equipment and musical instruments are provided via donations. I taught an SAT class here and several students routinely could not attend the full 4-hour practice test because they had to baby-sit siblings until their mom got home from her overnight shift or themselves had to go to work. I had several students who worked full time jobs while going to high school, doing 4-midnight shifts at local restaurants or other service jobs (laundromat, etc.) and then going to school at 6:30 AM.
When families are living at an income level where they are fighting just to survive, it's easy to see how there just isn't time or energy left for the involvement that great public schools require. It's easy to see how back to school night or parent-teacher conferences are as realistic as a trip to the moon, why a fundraiser yields very little, or why few parents volunteer in the classrooms.
This isn't to say that throwing money at the schools solves the problems. The per-pupil spending in my town is the 5th lowest in the state, because we have enough parent volunteers, PTA and booster money to offset our meager budget as well as parents who can buy sports equipment and musical instruments. Some of the worst schools in our state have the highest per-pupil spending. So that's what I mean when I say that it's about the money (family) and not about the money (school).
I don't think it's about bad parenting per se, but about parents who are themselves poor, uneducated and simply ignorant. They probably went to crappy schools and had poor, uneducated and ignorant parents themselves. They are not mature enough nor do they have the knowledge or resources to advocate for their children. If they did, they wouldn't live where they do.
I certainly don't think it's teachers. Yes there are lousy teachers out there, but teachers in underperforming schools have the deck stacked against them.
I had the chance to do a community service project at a charter school in LA last week. The public school in the neighborhood had a drop out rate of 50% and college acceptance rate of 10%. This school, run by a private educational corporation, had a 98% graduation rate and 92% college acceptance rate, with most of those kids going to four-year colleges. Now obviously, the school was able to select only those students with the aptitude and desire to commit themselves to their education and succeed. Public schools are much larger and have to take everyone, including the kids who don't want to be there. However, this to me made a very good case for charter schools and reinforced the idea that sometimes, a micro approach can be really successful.