They don’t care as long as most of the people stay fooled most of the time. From Caitlin Johnstone at caitlinjohnstone.com:
One of the most consequential collective delusions circulating in our society is the belief that our society is free. Our society is exactly free enough to create the illusion that we have freedom; from that line onwards it’s just totalitarianism veiled in propaganda.
I get comments from people every day wagging their fingers at my criticisms of western imperialist agendas against nations like China or Iran saying “If you lived over there you wouldn’t be allowed to criticize the government the way you criticize western governments!”
It is true that dissidents are permitted to criticize the government systems of the US-centralized empire to an extent, but only to an extent. Yes, as long as my criticisms of capitalism, oligarchy and imperialism remain relegated to the fringes of influence I am indeed permitted to express my views unmolested. If however I somehow ascended to a position of significant mainstream influence I would be targeted and smeared until my reputation was ruined or I had a psychological breakdown and went away. You may be certain of this.
The managers of empire do not work to crush and silence all dissent like a conventional totalitarian regime would do. They are much more clever than that.
In a society that maintains the illusion of freedom in order to prevent outrage and revolution, it does not serve rulers to stifle all dissent. Just the opposite in fact: their interests are served by having a small number of dissidents hanging around the fringes of society creating the illusion of freedom. If Johnny Hempshirt over there is allowed to stand on a soapbox and criticize the US war machine, then the US must be a free country.