Syag > afraid of them learning too much from the wrong people.
Are you advocating for kids being sent to public or open-modern schools with no supervision? I think our whole educational system is built on shielding kids from bad influences and you seem to agree with that. Consider, as an illustration, a poster here who is a teacher and tends to feel very negative towards any derech except his. I can imagine him being my kid’s Rebbe and I would come very satisfied about his knowledge and middos based on a short discussion. At some point, i would notice that the kid is becoming less and less tolerant and becoming stubborn in his Jewish and political views. Ok, I guess I can wait until he grows into his 20s, and then, I can talk with him as an adult and train him into better thinking. I would feel the same if the teacher will have modern or zionist or chassidic biases.