how and when you know it’s a necessity

I did the math actually. And it seems like mass surveillance will only be justified if homicide rates are higher than 20% ( if 1 out of 5 people die in murder ). And only if surveillance actually stops all the crime ( which it doesn’t ) and only if there is nothing less problematic that could be used instead ( which there are plenty techniques, like normal regular investigation, where you ask people around on their own terms ). Basically the math says it isn’t justified by an apocalyptic margin.

As always, they use a mildly annoying problem and try to solve it with absolute apocalypse.

It’s proprietary.