This. 7 million people seems like a lot, but it's not. Out of that maybe 1 million were serious protesters. Of that the facial recognition can zero in on who was there. From that algorithms can sort people based on family ties, net worth, etc. You're then left with a list of about 10-20k people. Now stretch that over the next 3 years and disperse it over 10 cells of death-squads. All of a sudden it isn't so unrealistic.

People don't understand how finite the world is.