Speaking of Germany, it allows private schools, even religious schools. But all these schools have to teach a basic curriculum, made by the government (e.g. evolution). That is to maintain a certain standard for all students, and to keep the graduation comparable.
How many languages do German students learn? And when do they start to teach them? I had to study 1 language and they didn’t start teaching that to us until I was in jr. high (14 years old) - which in my opinion is rather late to learn another language.