The trash bins were enabled to listen for the unique MAC address codes that every passing laptop, tablet, and smartphone offers up when hunting for Wi-Fi access.23 Using this data to estimate the number of unique passersby who saw the ads on the bins would let advertisers measure the impressions and value the service. But it also could make people feel spied upon in a public place. The local governing authority, called the City of London Corporation, decided it was a privacy-invading step too far, and it required the company to stop such tracking.
