"Once a city is routinely surveilled, the government can turn every indiscretion into a criminal matter. You used to be able to speed down the street when you were in a hurry. Now, in many places around the world, a speed camera will record your behavior and send you a ticket in the mail. Combine cameras with facial-recognition technology and you’ve got a recipe for governmental intrusion. Did you just roll a joint or jaywalk or spray-paint a bus stop? Do you owe taxes or child support? Well, prepare to be investigated—if not hassled, fined, or arrested."
An idea also notably absent: the current amount of surveillance we stomach as a nation has helped and continues to help in many criminal investigations.
From what I understand about terrorism, many times the terrorists don't get a chance to leave the scene.