The need for security in underground parking garages

These washrooms look like they're right out of a 5-star hotel of the future. It is very unusual to see such clean state-of-the-art washrooms in an underground parking area. Since underground parking areas are notoriously dangerous, the architecture includes decoratively installed security cameras:

Finding hidden surveillance cameras using electronic flash and a sousveillance camera

Closeup view shot using 400mm telephoto lens on the sousveillance fails to see through darkglass (greyglass):

Using off-axis electronic flash helps:

A high power electronic flash off-axis, can make visible the hidden surveillance camera, if the flash is powerful enough, and a dark enough void can be found at angle of incidence equals angle of reflection into the sousveillance camera: