Could we clarify this a little? Are we talking about head scarves, per se, here, or does that include the "bhurka" (sp) type garb that that Florida women refused to take off for her driver's license picture (thus making it useless).
I've always wondered, if she was so "religious" that she couldn't remove the garb, why did she need a driver's license?
The Christian Ladies' head vieling does not cover the face. The most extreme of these would be what the Catholic Nuns wore a generation or so ago.
The most common of the Christian Ladies' head veiling is what you see among the Amish and Mennonites, somewhat of a gauze bonnet. Often the veiling may be a plain kercheif that covers the top and back of the head.
There is no need to obscure the Christian Lady's face.
In the case of the Muslim lady who wanted a drivers' licence, if her face is obscured, and her peripheral vision compromised by the burqa, then she must be denied a drivers' license and be willing to endure that sacrifice for the sake of her religion.
Many Christian women were burned alive (or worse) for their refusal to deny their faith in Christ. Certainly, doing without a drivers' license does not amount to such punishment.