I imagine this is because we are dealing with a people who feel that they are morally superior than the rest of the world due to worldly advantage and dominance.

Whether or not this school was correct in their dress code [1] is shadowed by the immediate conclusion for many that “Islam = Bad, oppressive, unfair, archaic” the moment that it ceases to be just an “internal, private belief for some” and becomes an external way of life that sovereign countries implement in their own territories. This is so even if what a country is implementing is not congruent to the tenants of Islam (see, the flogging of the Homosexuals for example).

Let them (viz. The West) tell it, the sociocultural climate of their localities are in exemplary order.

[1]: I see no issue with private institutions enforcing a dress code that makes the hijab mandatory. Non-muslim students need not attend and even to force them to wear it would obfuscate the intent of the hijab. It is far more than just a cloth that is draped over the head of any woman and its virtue is neglected so long as its wearer is void of virtue herself.