Once you take this step you legitimise the idea that there is an authority with the power to censor - ostensibly for good reasons - and sooner or later that power will bend somewhere else.
It's important that children learn about everything, especially about opposing ideas because only then can they form their own opinions and develop critical thinking, and most importantly the ability to reevaluate an idea based on changing data.
To paraphrase your analogy I prefer my children to only learn about the US healthcare system, and not waste time learning about how other countries do it for better outcomes with less money.
And this is the problem with your post - who decides what is OK, and what is a waste of time?
Ps - I am upvoting you not because you are right, but because you add a valuable perspective to the conversation, and I support your willingness to bring it.
Assuming you mean what you wrote, you may be arguing for abolishing the public school system. In principle that seems like an interesting idea, but the rest of your post isn't quite congruent with that so it seems possible you've missed that this part of the thread is about school curriculum.
I don't have a problem with that, and I don't have a problem with teachers bringing their own personality to the classroom. I am not vegan, but if my kid has a vegan teacher that would be valuable in exposing them to that world-view.
I do object to political interference in education. When the govt decided what material is OK, and what is not, then you remove the variety of thought which exists in the world. And ultimately that leads to a lack of personal critical thinking which leads young (and older) adults to belive anything.
It is hard for the government to control the school system and also for the government not to exercise any control over the school system. I think you might be advocating voluntary, private-only schooling here - although I also think you might disagree with that opinion.
I guess my primary point surrounds censorship, especially when it comes to dictating what teachers can say or teach (in addition to, in the context of, not necessarily in place of the cariculum)
Or how about this analogy, Zambia is a real county with real history. However, I care about what American kids learn. While they can spend a week learning about Zambia (and Tajikistan, Gabon, Kiribati, and all 200 world countries [taking 4 years]), I would prefer that they spend that time doing something else more important just as US history. So I would like to restrict the amount of world history from the curriculum.