That I have strong disagreements with, Jack. Twenty people -- ordinary people, not a mob, cold, torn away from their familiar haunts and/or separated from their loved ones -- are sitting there. One guy gets bold, runs and kicks over a drone, scrambles for the elevator, gets in. "C'mon, we can do this!!" The drone gets to its feet, is joined by two more, they go into the elevator and literally slice the guy apart with chain saws.
Now. You're one of those 19 'other' people. Are you gonna rebel??
Control through threat of violence by the one against the many depends on the individual being kept an individual, not being allowed to group up. You get this in a lot of Westerns, but going the other way around.
[LEAD Member of MOB]: "Bring him out, Sherriff, we're gonna lynch him!!"
[SHERRIFF]: "Well, I can't take you all on ..."
[MEMBERS of MOB]: (Various) 'Yeah!!' "That's right!!" "You can't stop us!!"
[SHERRIFF]: "... but the first three men that step up to get him are gonna get bullets in the belly. Now that's a death sentence. You gonna be the first to die, Wally? Pity leavin' Emma all alone on account of this rustler. How 'bout you, Clarence, with your three kids and another on the way? Or you, Buck? Don't you got that money comin' in from Texas soon?"
The one, whether Good Guy Sherriff or Bad Guy Deus, makes sure the many understand the close, personal destruction that's going to happen to them if Problems Happen. Keeps them from getting up the courage to accept themselves as a possible loss in order to get the job done. With the effectiveness of a few 'examples' of utter ruthlessness among large groups of people, you certainly wouldn't need to make many in order to ensure that the rest were going to not want to be the next one.
Consider the Holocaust. A comparative few terrorized, controlled, and dominated tens of thousands daily, and literally millions of them during the course of the war, 'just' by utterly ruthless application of violence and pain -- combined with the hope of 'one more day of life'. People can be cowed, and cows can be herded. Counting from Kristallnacht to V-E Day (2,371 days), during which 11 million were killed, you get an average of 4,640 per day. Considering the Arcology, I'd say no more than 10,000 were slain for purposes of control in the first 60 days. Yeah, that's a lot, but over 400 floors, that's only 167 per day -- one person per 50 people every 2 weeks. Not bad for reminding people that if they live five more minutes it's because they aren't causing trouble.
This doesn't count experiments, of course, but hey, you can't have everything; where would you put it?