The bottom line with both of these technologies is that their usecases are simply too narrow to inspire causal use. The radar-gadget is useful if you're about

The bottom line with both of these technologies is that their usecases are simply too narrow to inspire causal use. The radar-gadget is useful if you're about to storm a house full of armed adversaries - in most other cases, you can just peek through the window or knock on the door and get much the same information. The laser-bouncer is great for eavesdropping on people who take some effort to hide their communication - if they don't, hiding a wireless microphone or a high-capacity dictaphone is orders of magnitude simpler and cheaper.