The capitalistic world state system was only completed in the last 50 or so years and was of course seconded by the Stalin machine. Its purpose is in the first instance to keep working populations in place, which is why all the states agree to it as they form. The system holds solid where capital moves (as did 'communism' and Comecon) but the peoples don't.

It is only when you think of individual states and not the system that you can fail to notice that we get the same result if they all try to keep their citizens in, and if they all try to keep the others' citizens out.

But that's just one extreme example. States based on Marxism-Leninism and Maoism in the 20th century often required things like internal passports to travel within a republic's borders. If the state didn't want you visiting family in another part of the country, you weren't visiting family. That still applies to some extent in a few modern single-party socialist states.

My larger point is, a lack of ethics consumes most economic systems, because you can't easily gauge ethics like you can quarterly profits or the output increase brought about by the central committee's five-year plan. Humans tend toward math over empathy in such situations.