Freedom, only with a green code

Several weeks into the COVID19 epidemic the Chinese government came up with a coding system. Based on where you had been, a QR-code on your phone turned green (safe), yellow (had been near someone infected) and red (stay inside, you’re infected!). At first, the system was implemented in Wenzhou. At this stage, it was unclear how it worked. Was the government really capable of tracking all location data on your phone? Later, it became a common method to keep track of the population, and restrict travel for those in areas where the virus flared up.