I'm going to be the glass half empty guy; I only see negatives here. I'm sure there are some positives - earthquakes, tornados, tsunami, chemical clouds, terrorist bombers, mad axemen on the loose, pilotless aircraft with snakes roaming free - but just for starters, a overly reliance on technology is never good. I was away camping recently and someone went wild swimming. His Apple watch began acting up - an alert going off randomly - culminating with it automatically calling the emergency services (these things monitor your heart-rate and make automated calls) and him having to forcefully persuade them that he really did not call them, and really was in no need of an ambulance!
Secondly, unless these alerts are going to tell you exactly what and where the problem is then they will just cause worry and alarm. There will be false positives. The Track and Trace App alerts you if your "Covid-19 ridden" next door neighbour has sat on the sofa on the other side of the wall
to you, or even in the flat on the floor above you.
You need to be able to evaluate these risks yourself, and therefore you need more information than a siren. The emergency procedures for fire, earthquake and tsunami can be totally different instructions - New Zealand have three different sirens for those - and obviously, those instructions need to be tailored to specific locations and buildings, rather than a one-size-fits-all.
Thirdly, I can't get too political, but having excessively worried and anxious citizens is a good way to control them and make them vote towards more extreme measures on the grounds of public safety. If Covid-19 hasn't been enough to worry people recently, they want to have them dancing to the strings of a phone alert too. I'm sure that isn't the intention here, but it could be seen as very sinister.
Fourthly, putting apps on your phone without your permission or knowledge? When did that become okay anyway?
do wonder what will happen to people without mobiles, or who currently don't have a signal.
People without the latest mobile phones have been side-lined for a long time now, especially those without smart phones, and those without a phone at all, they're pariahs! So, nothing new there. Don't have the Track and Trace app or a phone number, then you can't come in! Don't have the Breweries own app to make an order, then you can't sit outside in the pub garden! Want tickets? You can't book them without the app. Paper timetables? Get the app! Can't get that required app, then your phone must be more than 3 years old! That's an old phone apparently!
People without a signal - despite the advertising that says they have 99% signal coverage (they mean of the population not of the geographical area) there are large areas with no signal, usually rural valleys with few people. Obviously, it is far too expensive to actually achieve 100% coverage via phone masts. There was an idea some time ago to piggy-back signals between phones. So, if for example, there was a line of fell walkers and the person in the front had a signal, then that signal could leap-frog its way along the line however long it might be to the back, hopping between phones. You wouldn't need to be in 'radio sight' of a mast, but only in 'sight' of another phone, which was in sight of another phone... which was eventually in 'sight' of a mast.
I've no idea what happened to that idea, because I never heard of it again. Maybe rural folk just don't complain enough about being excluded from the modern world.