Some public schools are weak. Other public schools are rigorous.
Some public schools have gang problems, drug problems, lots of kids who have uninvolved parents who don’t emphasize the importance of getting an education. Other public schools don’t have to worry about gangs, or drugs, or have a high proportion of educated, involved parents who encourage their kids to learn.
But when you look at private schools— private schools, by their nature, tend to attract more of the Involved Parent Demographic. Because you’re suddenly paying $2k, or $5k, or $10k a year/semester/whatever for your kid’s education, not putting them in whatever school your geography dictates.
And when you pay $2k, or $5k, or $10k a year/semester/whatever, you expect certain results… because otherwise, it’s not a good investment. And so the schools strive very hard to live up to the parents’ expectations.
I went to public school for a bit. I also had the opportunity to go to Catholic school. The thing that really stood out to me on my first visit before enrollment was-- “Wow! The kids are so quiet!” Because they were bent over their work and working, not chatting and goofing off. They had focus and discipline and knew how to act, unlike the kids at the public school I was attending.
The public school kids, you get a wider strata of society. The private school kids, they tend to come from a more homogeneous background. Not necessarily in terms of income, but we were in a University town, and so a lot of our parents were high-achievers in some way or another, and because we were Catholic, a good proportion of us had grown up with that faith background to color our worldview of our place in the world.