Finding the Needle in the Haystack

With today's sophisticated technology, finding the proverbial needle in a haystack is probably easy, and finding the face of one individual in a crowd of 60,000 people using CCTV cameras is doable as well. China has 170,000,000 of these cameras installed with another 400,000,000 to be installed in the next few years, which will make it very hard to escape the eyes of the law, and maybe the eyes of more ominous people. Like most technological tools, using facial recognition for social purposes can be both beneficial and harmful. Will all modern countries allow almost unlimited police use this technology, and should they?