For the past two weeks, I’ve been using a new camera to secretly snap photos and record videos of strangers in parks, on trains, inside stores and at restaurants. (I promise it was all in the name of journalism.) I wasn’t hiding the camera, but I was wearing it, and no one noticed. I was testing the recently released $300 Ray-Ban Meta glasses that Mark Zuckerberg’s social networking empire made in collaboration with the iconic eyewear maker. The high-tech glasses include a camera for shooting photos and videos, and an array of speakers and microphones for listening to music and...