>And what of it? A lion has a difference of opinion with you about whether you're its dinner. Do we need to spend a trillion dollars and have a war on lions? What about Streptococcus? It's alive, it adapts, it wants to kill you, another trillion dollars?

The point about lion is good and that's why our ancestors had spent a huge amount of resources (money, time, hunters etc) to "eradicate" lions. Due to our ancestors' efforts and the consequential huge spendings towards this eradication, today we don't have to worry too much about the opinions of lions. Today the lions are rendered as what we proverbially call "toothless tigers/snakes".

A similar argument can be made about Streptococcus or (any such bacteria/virus or even any other such animal) and humans want to be in charge of things so much so that their opinions and thence their consequential actions do not become a significant danger/hazard to the humans.

Many fanatical animal lovers do hate this idea (of humans wanting to be in charge/control of other animals) too. But that is a different story.

Now with terrorists, the things become different in a very important manner. Lions and other animals are different species and thus their eradication problem doesn't first pose a very difficult "identification" problem. To deal with human terrorists, first we have to "identify" them and their sympathizers who can/do provide safe harbour to them and thus help the terrorists in their intended terrorist actions. This "identification" problem is what requires mass surveillance. This brings "cancer" to my mind, as in case of "cancer" also we face a very "identification" problem: problem of identification of dangerous cells.

Hope this helps.