First of all, Glass could've been turned off. Second of all, she could be using it for GPS and other things.
Personally, as a driver, I'd prefer to have all my car information on some kind of a HMD, and not on the dashboard, where I have to look away from the road.
I'm going to go out on a limb and assume you don't drive much.
I spend a lot of time on the road (60,000+km this year). There are a multitude of things to distract you behind the wheel, from eating, phones, stereos, day-dreaming, other drivers, nature, whatever. It's endless. If having a small eye piece is distracting to you, by all means don't wear one. But don't project your inability to maintain focus on all other drivers.
I personally fall on the other side; why not extensively test before banning. We live in a society that jumps to conclusions. I believe we should have a proper understanding of something before deciding to make laws relating to it. What about the positive benefits. Also, do you really expect them to do the research after banning it? Look how long it has taken the FAA to even start reducing the ban on mobile devices.
I've lived in a country which forbade everything by default unless law explicitly allowed it. I guarantee you don't want to go this way.
Definitely agree with you that I'd prefer a HMD or HUD in general to look-down instrumentation.
A general purpose head mounted entertainment system that may or may not be used to display GPS along many other things while driving is a terrible idea.