A country's people is its citizens. What you're describing with the EU is open borders between countries. The EU is not a state or country under the definitions created at the peace of Westphelia. Ironically the solution over fighting over the same type of issues in the same geographic areas, although in the name of uniformity of religion instead of closer integration/market uniformity.

Small-state citizenship relates to the discussion as one point of comparison as to super-state unity.

The United States really is one country, and is Constitutionally required to maintain unity, to have only one front for international affairs, and to allow U.S. citizens to be citizens of the state in which they reside.

None of these is true in the EU. EU member states are permitted to leave. Each EU member state carries on its own foreign relations. Each EU citizen maintains citizenship in the EU member state of his or her birth.

The EU is not at all analogous to the United States after the Constitution of 1798 and post-Texas v. White. There might be an argument that it's similar to the United States under the Articles of Confederation. Any insistance that they are more similar is a false equivalency. That is the point of GP.

I never said EU is one country but the OP said: "It’s not as easy for a Bulgarian to go live in France". Which is false.

That is not correct. The quote is "It’s not as easy for a Bulgarian to go live in France AND claim French citizenship compared to a Californian fully moving to Texas" (emphasis added).

In the interest of promoting honest discourse, please do not truncate people's statements. If a Californian "fully" moves to Texas, i.e., establishes domicile there, then they become a citizen of Texas. That is a key difference.

ok then I misunderstood the original post. The way I understood was that those are two different actions 1. Bulgarian live in France, 2. Bulgarian claim French citizenship.