But the identification problem isn't unique. It's true of every crime there is. Criminals don't come with tags labeling them as a terrorist or a murderer or a pedophile. And there is nothing you can ever do to eliminate 100% of all crime. It's about the most cost effective way to provide enough deterrence to keep the crime rate low. And mass surveillance has a huge cost in privacy and in money and in security itself. It's a terrible trade off.
> This brings "cancer" to my mind, as in case of "cancer" also we face a very "identification" problem: problem of identification of dangerous cells.
You're kind of making my point. Cancer kills way, way more people than terrorism. Why are we spending more resources fighting terrorism than cancer?