I'm not sure what you think you're saying here. You might have noticed that in something like 90% of the countries on the planet, that country's government is dominant over the entire country? Dominant only means that nobody is capable of challenging them currently for the title of being in control of the country, not that they have total control over everything that happens there.
Yeah, but you always have the possibility to flee your country (legally or illegally) and go in a "better place" (how much better that is depends on where you come from) - but once you have a single government controlling every place on Earth, that possibility is removed.
