Because getting told when you were eating at the same restaurant as someone with a contagious disease could be life-or-death information?
(Mind you, I've no intention of going to restaurants until the infection rate is much lower!)
Why not just use the double blind google / apple tech for this? The govt requiring this level of data seems unnecessary.
To my knowledge there's no implementation of that tech. I think it's definitely not an ideal system to have it be all pen and paper, but there isn't a clear "just turn it on" solution they're ignoring here either.
There's a pandemic happening right now, so I think they're doing it to track where people go and how things might be spreading. It's really helpful for analysis. I think people are handing info over because it's required to get one's order.
Because it's the law and majority of people obey the law. You'll get an odd person who refuses, but that's fine, they can leave if they don't want to comply. Unless majority refuses to comply, nothing will change.