I don't think you understood what I was referring to.
I was making an analogy between countries and fiefs. We have more or less the same freedom to move about as serfs did. And I mean "we" as everybody, not just the few privileged people who fall into special categories allowing them to go live and work wherever they want.
The problem is that there is no one "international system."
Again, I don't think we are talking about the same thing. There is an international system to which all countries belong to, which enforces the very entity of a nation-state, or country, it's borders, the entitlement to its own laws, etc.
This is the one international system that everybody must play by. And it is very feudal.
I think what you meant is that there isn't one international system as if the whole world were one country. That's what I was pointing to, because it's this fragmentation into fiefs dressed up as countries that chains people to their original fief (country) and largely impedes mobility, freedom of choice, etc.