You are assuming it's about the curriculum it's not. It's about the environment, the parent participation etc.
Therefore I can't see why you think I assume it's only about the curriculum.
Nor do I see how unions are relevant. Your 1960's classroom, in the cartoon that resonates so strongly with you, was almost certainly run by a union teacher, in a time when unions were much more powerful than now.
You can't decide to choose one part of history and not the other.
Do you have any evidence that that's actually true? My examples demonstrate that it was far from universally true in the 1960s.
If was was true, when did it change? There are plenty of complaints in the 1970s complaining about how the parents are at fault. In fact, I can find complaints from the 1940s about how the young people these days have things given to them on a platter and never have to face any challenges.
If it isn't claiming an actual historical propensity, why does it use "1960"?
And if you think the highly unionized school teacher of the 1960s was effective, then why do you think unions are the problem now?
For example, this 1995 article describes how a school for the blind was closing because of the mainstreaming of blind students. https://news.google.com/newspapers?id=_DRQAAAAIBAJ&sjid=pVUD... . Here's a recent example of a teacher using the term 'mainstreaming', http://curmudgucation.blogspot.com/2015/10/pa-shutting-down-... , and doing so only in the context of special ed.
Either your school district was using its own definition, or you misunderstood the context.
"Well-rounded education" was a bigger buzzword in the 1940s and 1950s. See https://books.google.com/ngrams/graph?content=well-rounded+e... . It's part of the American education system that students are required to take course in a diverse set of subjects. It doesn't require that everyone take the same classes.
That clarification aside, and assuming I'm completely wrong, how does a charter system, which presumably has the same general graduation requirements, change things?
Anything more about your circumstances requires understanding more about your district. Eg, was everyone in the same level of math, so that no one (or everyone) took calculus by the time they graduated? Were there only 25 students in the class? Did everyone take the same foreign language course?
Wow! My school has changed. There's a "Drafting / Illustrative Design Technology" track, a "Fashion Design" track, which includes "Fashion Marketing Management", an "Arts, A/V Technology & Communications" cluster, and more http://www.coralgablescavaliers.org/apps/pages/index.jsp?uRE... .