Exactly East Berlin, actually.

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.