parent edited their comment which originally was just the first paragraph about centralised control, I suppose that's what you are replying to.

Obviously it is hard to quantify control so I don't have hard numbers to present, but I ask you: can you name a more efficient surveillance device than a smartphone?

Note that smartphones became ubiquitous very recently, I would say during the last 10 to 15 years (before that, they did exist but were used by a tiny minority of people).