Earlier quoted context omitted.
Proof is not required. In the US, for example, you file taxes on an honor system. If you've lied, there are periodic audits, and you might get thrown in prison. I assume you can lie going to China. If you do and get caught, you'll probably never be welcome to visit China again (or fines, or prison, or some other consequence; but most countries would just keep you out).
Proof is not required it always depends on who is asking. this whole subthread is about who the GDPR applies to. in your other comment you lay that out very clearly: https://news.ycombinator.com/item?id=31397369 the relevant question is: when do i loose my status as a resident of the EU if i am an EU citizen. i'd like to make the claim that the intent of the GDPR is to protect the people who are inside the EU at the…
https://gdpr-info.eu/art-3-gdpr/
However, the framing as a human rights law, protecting "fundamental rights and freedoms of natural persons," means that the intent is somewhat more broad:
https://gdpr-info.eu/art-1-gdpr/
It defines principles which are believed to apply everywhere.
That's reinforced by language like "This Regulation applies to the processing of personal data by a controller not established in the Union, but in a place where Member State law applies by virtue of public international law." This extends jurisdiction as far as practical, in ways which are legally ambiguous.
"Legally ambiguous" generally means that you might be right, but the cost of finding that out will be astronomical.
Human rights laws have an inherent friction to them. On one hand, if random dictator's private business violates human rights laws, that's outside of jurisdiction, so not much can be done about it. Sovereignty is an important principal. On the other hand, it's clearly viewed as not okay, and often has some ramifications at some point. If you're applying for a contract, and have a track record of human rights violations....