Surveillance is regarded negatively in the European Union. It is, of course, highly enabled by the Internet, especially by smartphones. Under modernity, and digital modernity in particular, however, surveillance does have its uses: it can facilitate coordination of complex social functions; it is a means to the personalization, recommendation, and negotiation of choice; it can also be used for care and welfare systems, or control of desirable outcomes, such as the reduction of carbon emissions. The 2020 COVID-19 pandemic is an area where surveillance has played a role, by gathering data, enforcing lockdowns, and particularly enabling the tracking and tracing of contacts by smartphone apps, to suppress the spread of the virus by asymptomatic carriers. The patchy implementation of this function is reviewed, together with some of the technical issues that made it harder than anticipated.