Why do billions of people still not have glasses?

Making spacecraft is not a job in which you can afford to be slapdash.
At Lockheed Martin, for example, it used to take a technician two painstaking days to measure 309 locations for certain fasteners on a particular curved panel.
But according to Shelley Peterson, the aerospace company's head of emerging technologies, the same job now takes little more than two hours.
What changed? The technician started wearing glasses. but not just any old glasses: specifically, the Microsoft Hololens.

It looks like a bulky set of safety goggles. And it layers digital information over the real world. in this case, it scans the curved panel, makes its calculations, and shows the technician exactly where each fastener should go.