You're confusing the US's requirement for religious freedom with the education model. It's not like you're forced to pick a school that teaches things you don't agree with.

For every one of these schools teaching kids religious nonsense that is clearly wrong, there is some other school using that freedom to try alternative ways of running classroom. If you don't allow this you end up with a pretty rigid system that basically everyone but educational board members hates, like the Common Core requirements that are so tight that teachers basically have to design their entire quarter around them.

If they receive public money, they may not introduce religious concepts into science courses. A chain of charters in Texas does indeed seem to be working around the ban on religious doctrine, a ban tested in court, by using tricky language e.g. "Evolution is one theory; there are competing theories." However sooner or later they'll probably be taken to court and lose. Probably nationwide, 99% of charter schools are secular and do indeed teach proper broadly accepted science and other subjects.

Don't send you kids to such schools?

That’s true. If public schools only focused on lower grade levels that would free up resources tremendously.

I agree. But go beyond elementary school and you’ve completely lost me.