How does wearing a hijab in a French public school go against French secularism?
The question deserves to be asked, but if you want to know why hidjab was banned in France, you should read the reasons given for it more carefully, and not at the level of general principles. Nowhere it is said that hidjab harms people. The main reason is that in the buildings of a secular state, people have to be secular in their way of dressing, and they mustn’t show off their religious beliefs. In a Moslem space or building, you’ll have to behave properly and not walk with your shoes on, whatever you think about this custom. The same for French schools. They are secular, so you have to behave secular as long as you are there.