It is just not an option for government to do nothing on vaccine passports. These have already been developed in the private sector. The major risk of immunity passports - that is, weaponizing immunity - are much, much higher with government inaction. https://www.telegraph.co.uk/global-health/science-and-disease/tony-blair-believes-covid-crisis-demands-completely-different/
People want to go back to normal, these are going to be used in some form whether the government do it or not, so surely it's better to ensure they're done legitimately? Let's not have the track and trace argument alllll over again
Also the risks of immunity passports extend way beyond weaponizing immunity and the haves vs the have nots. If they don't regulate them, the concept of 'immunity' (which is v fluid) could be oversimplified, breeding inconsistency, and anyone could start requiring them anywhere
Digital health passports, including testing and vaccine, are by far the most effective non pharmaceutical way of managing the public and individual health risk. Much more precise, much more targeted, real time assessments of health instead of disputed predictions of transmission.