Within weeks of Covid-19 shutting down the world in 2020, teams at archrivals Apple and Google partnered on a rare joint project. They developed a way to log people’s proximity using Bluetooth chips in iPhones and Android phones, enabling the creation of apps that let someone who tested positive for the virus to anonymously notify fellow users whom they’d been near in the preceding few days. Those alerted to the exposure could then isolate, test, and quarantine, hopefully slowing the spread of Covid.

Covid is still around, but the grand…