Why can't big tech self-regulate? Why must it always be a solution that depends on big government instead? Why should anyone trust the government given the last few thousand years of history?
Though in many places governments aren't great at preventing theft and violence. That's why even in developed countries, many companies hire private security, citizens learn self-defense, and some people carry pepper spray, knives, or even firearms.
Even in the case of a dictatorial and lifetime head of state, separation of powers is baked into the cake by groups with common interests, sometimes organically, sometimes on purpose.
Of course any sufficiently big organization does have competing departments with conflicting agengas, but also there are nuances.
Personally, I think that the government vs. industry split becomes rather academic when you are speaking of monopolies, especially monopolies that spy on you. I expect that there's a slow motion merger into a GoogleFacebookMicrosoftApple.gov body with the companies acting as cabinet branches.