Because its all about forcing compliance and keeping tabs on dissidents. The government already has a list of all its citizens etc, this is just so they can usher in the vaccine passport system and use it to create pariahs and eliminate anyone who maybe says the wrong thing, votes for the wrong guy, goes to a protest, posts the wrong content on social media etc. It's setting the stage for a social credit system. You could just switch any dissidents status to infected and label them a public health risk and exclude them from society or haul them off to an isolation camp.