They have enough money to pick out individuals and hound them by low-tech means. They don't have the manpower (much less the money) to monitor everyone in a nation of 350 million people. I can run through the numbers again, since no one here seems interested in or capable of doing it, but the result falls in a vale between impossible and infeasible.

Why do you accept that you would allow things to get to the point of absolute tyranny? You don't plan on doing something NOW to prevent that? (Flock cameras are not in any way essential to tyranny. But when vandals get caught and shot, the vandalism will be less appealing. You don't really understand how a tyranny works. They don't have to worry about "how it looks.")