the bathroom stalls were slightly green tinted (otherwise clear) glass. Awkward, but I guess when nature calls…. Anyway, when I stepped in and closed the door and flipped the latch, all of the glass instantly clouded to the point that it was opaque. I figured that was a smart glass application that we would soon see everywhere, but I haven’t seen it since.

Maybe the guy in the OP was experiencing a facility malfunction.