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.

the answer is.. it's subjective, you just make up your own mind, and justify it with : it's a necessity, may Allah forgive me 🥺👉👈

The answer is when you are in a death situation.

No wonder, though. It seems like you don't even intend to learn facts about the religion you'll believe in.