Because, as Cecilia Abadie recently found out, you might end up getting a ticket.
Pulled over by San Diego police, she got a ticket for wearing the smart glasses while at the wheel just days ago. She explains:
A cop just stopped me and gave me a ticket for wearing Google Glass while driving! The exact line says: Driving with Monitor visible to Driver (Google Glass).
Clearly, Californian police feel that the display on Glass is as distracting as looking at a phone. It's not obvious if that's really the case or not—but it'll be interesting to see what lawyers and judges make of it. What do you think? [Google+ via Engadget]