You're lucky to have great teachers, and I just think we need more of such kind. As for bad schools, let me give you a few examples and you can check out the documentary Waiting For "Superman" to get a more grim picture.
- Did you know that teachers in some Cupertino schools asked parents to grade student homework?
- Did you know that a straight-A student who graduated high school in NYC couldn't pass the math placement exam in The City College of New York? I mean, placement test in a college, how hard could that be, right? The story was featured in NYT, IIRC, a few years ago.
- Did you know that only 48% of public school students who took the California Assessment of Student Performance and Progress (CAASPP) met or exceeded grade-level standard in 2016. And we're talking about CAASPP, a standard that is really not that high.
- Did you know that SAT is not differentiating to say the least, yet the average score of SAT math in California is merely 536. Pathetic, shall we say?
- Did you know that elite students in the Bay Area routinely completed more than 10 AP classes, yet the average students could barely understand Algebra 1?
And now let me give a few counter examples to show what good teachers can do to students:
1. All 14 students in Jaime Escalante's class passed AP Calculus I back in 1982, even though the school was in a hood. The success was so shocking that people thought the students cheated.
2. KIPP. Merely extending the school time to 6:00pm and offering classes in summer helped students stay in school and make steady progress towards entering college.
3. Schools in other countries. Take the schools in China, for instance. Teachers enforce cultures. Great scientists and philosophers and writers become household names because of them. They form research groups to continuously improve teaching materials. Better ways to teach, better problem sets, better projects, and better exams. It is widely assumed that teachers are better problem solvers than students in China. Can we assume that in the US?
By the way, a student doing well in standard test may not be a good student, but a student who does not do well in standard test is definitely not good academically. I don't really see why people keep blaming standard test for student's miserable scores. Do we really think these students could solve much harder free-form problems when they can't eve deal with much easier standard test? There is a reason that multiple-choice problems are the easiest ones in other country's college entrance exams. It suffices to say that if students in a school couldn't even pass standard tests, then the school has failed the students.