there are AWFUL public schools and GREAT public schools and most fall in the middle.
I will comment on the ones in the middle. For a child who happens to enjoy learning in the rote, repetitive, structured environment that most schools provide, they can be a good thing. These children will be labelled as "Bright, above average, studious, smart, responsible, and on the right track." They will probably have fun in team sports and/or an extracurricular club like yearbook or French club, and go on to a good college and get a good job they like- and that is all fine by me! those are good things.
unfortunately, the system won't work for kids who like me, needed something outside the structured norm to interest me. If you sit me in front of a history book and say read 3 chapters, it's nearly impossible for me to retain any of it. If you instead take me to a museum, show me the artifacts, let me watch an interesting TV show on the subject, let me listen to a speaker who had a first had experience talk about it- I might actually learn something and enjoy it! it's not that I'm better or worse thant those other kids- I just learn differently.
There are other kids who need specific help developing certain skills, like reading or writing, because their brain works differently than others. In public school, they'll get labelled as stupid, thrown in a back room called "special education" and put in classes that are dumbed-down versions of the regular classes- though if someone had tried a different approach, they could learn as well as you or I, just in a different way. these kids won't have a good chance of going to college because of the labels the system has put on them.
my point is, it isn't that easy to make one big ol' system that you either do or die. everyone had better fit in, and if you don't fit the mold, there's something wrong with YOU, not IT. and I think that's wrong.