Let’s say you are walking down an urban street late at night. There is nobody else around.
A car pulls up and several people get out of it. One or more of them may be carrying a gun.
They demand that you hand over your belongings. Of course you do, because you really have no choice.
Now imagine it is several years into the future. You and everyone you know are wearing smart-glasses.
You use your glasses for all of the things you might now do with your phone or a card in your wallet, including shopping for groceries, entering a secure office building, paying your subway fare, and getting directions from Google Maps.
But unlike your phone, those glasses will be recording everything you see, all the time. So the moment those people approach you, their faces are already entering a database, and being matched to a list of possible identities.
In the future nobody is going to be crazy enough to try to rob you. On balance, this may be good.
Of course, there are real downsides to everyone having the power to record everything around them. But that’s a topic for another day.