Would people be more willing to use it if it didn't work on a phone, but on say a bracelet?
This has been suggested, and I can see a number of advantages.
– It would be available to people without smartphones.
– It would be obvious when we came to "mission over" and people would stop wearing the bracelets. There would be no chance of people forgetting, or not bothering, or not knowing how to remove the app when Covid track & trace was over, so there would be less opportunity for mission creep like this.
– It would be an expensive and very visible exercise for the government to renew bracelets in, say, a few years' time, so the physical/battery/software decay of the bracelets would itself provide a time-limit. This would mean that any "new missions" the government "invited" us to give permission for, using the app, would be subject to at least as much scrutiny as the Covid T&T.
– It couldn't interact with other software or website use or data on your phone. So there would be no risk of mission creep or data scraping using such interactions, and no problems with interoperability, and fewer challenges of making the app work on so many different versions and brands of phones.
This doesn't get around the fundamental issues of being tracked, or of people gaming the system with false reports or by leaving the tracker behind, of course. There would also be issues re manufacturing and distributing millions of bracelets.
But I saw it suggested elsewhere and wondered what people would prefer as users?