If you can see what is done with an smartphone how is there are such a number of subreptitious videos and pictures taken with smartphones
And yes, it is possible to make a surreptitious recording with any camera, but there is no comparison.
With other cameras including cellphones, it takes a tricky and intentional effort, with the risk of social consequences if discovered.
Glass is designed to make it ubiquitous and effortless to record people, with no indication to those being surveilled.