Muslim head dress is cultural. It is not religious. Those who have studied the Quran know that nothing in that holy book of Islam requires women to cover their heads, much less their faces. 

The references to head covering in the Quran parallel what can be found in the Bible. What's more, the wide variation in head coverings to be found among various segments of the Muslim faith further confirms that this is cultural. It is not religious. 

Requiring, at least for security purposes, that all people uncover their face is right and reasonable and violates no religious laws. Those who protest on religious grounds are not being truthful.