I see your point: You assume that in poor neighbourhoods schools get "sh*t in, sh*t out", the difference in achievements of students is affected by... hmmm... greater tendency of poor people to lack motivation and ambition to aim for college, for example, if it is obvious that the family could never afford to pay for the college anyway.
A valid point.
As a parent I would tend to be concerned about the potential impact of disillusioned and unmotivated peers on the motivation of my own children, and therefore prefer schools in which the peers are expected to have a positive impact on the studying morale of my children.
No, that was not my point.
At any rate, the colleges we could afford to send our kids to are not hard to get in to. My kids are better students than I ever was, and I was accepted to every college I applied to. I only applied to those we could afford, of course (in-state State schools).
Instead it is that the school ranking systems most commonly used here (such as Great Schools) rely too heavily on the results of the standardized tests. A school that gets a bunch of kids who are far behind where they should be, and moves them up to just a bit below, would get a worse rank than a school that starts with kids who are already getting very good test scores and show no improvement.
In this scenario, the school with the poorer test scores may only have poorer ranks due to the lower "starting point" of its students, rather than anything to do with student motivation or teacher quality. This in turn may be tied to the socio-economic factors such as the time parents can spend helping the kids with homework (tougher with single parents or parents working two jobs) and the educational or language background of the parents (harder to help with homework if you don't understand the homework yourself).
As for an update, we've decided to apply for the "choice" school on the other side of town, rather than the neighborhood school. My wife was motivated by the test scores, I was not. We were both motivated by a veritable tsunami of anecdotes from the neighborhood school about bullying, violence, and the school administration's poor response to it, as well as reports by about a dozen parents who transferred their kids from the neighborhood school to the choice school and say the environment is much better there.
My daughter and my son are both very good students (much better than I ever was). Daughter has ADHD and repeated a grade a few years ago (fourth grade) - she was passing academically but was very hard for her to keep up. We're talking emotional meltdowns during homework two or three times per week, still ending up in the bottom 1/3 of her class. The ADHD makes her seem weird to the other kids her age (but not to me, I love her eccentric sense of humor) and she had difficulty making friends and seemed immature and childish with kids her own age. Her mid-summer birthday meant that she was one of the youngest kids in the class.
So we held her back and worked with her Dr. on medication. She's sailed through the second try of 4th grade and then through 5th grade near the top of her class and makes friends more easily. She is the oldest kid in the class, but only by about two months. They might still see her as different, but are more tolerant of it because she can help them with assignments and produces amazing artwork. They gave her a nickname that she likes.
But, in the end, she is still a kid that is slow to make friends and comes off as eccentric. I don't want to send her a school that does not know how to deal with mistreatment of kids that don't fit the social norms. That was the deciding factor for me.
It is a hard choice, for me at least. We could keep her with her cohort of friends which is supportive, but only by sending her to a school environment that
many parents and students have reported as being very toxic. Even then, she only has one really close friend within that cohort, most of the rest are more like just casual acquaintances. Or we send her to a new environment where she will likely know few or no students, but in which the environment is more nurturing.
We'll go for the more nurturing environment, with the assumption that the good school environment will help her make new friends more quickly.
Sometimes parenting can require decisions that are not easy.