I guess the fly in urinal is a classic example of nudging technology.

Reminds me of the time that Feynman fortuitously identified a design problem in the plans for a uranium refinement plant

Safari's "Private browsing" mode is not intended to keep info on your computer (e.g. previous cookies etc) from being sent to web servers. It is intended for the reverse - to keep the details of your browsing session private from others who might access your account using that computer. I.e. it merely prevents records being kept about your browsing session.