Any Bulgarian may go to any EU country and get employed, no questions asked.

Citizenship is a different thing and I don't see how it's related to this discussion.

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.

It's very easy for a Bulgarian to go and live in France, that's the point. Claiming French citizenship is a different things entirely.

This is false.

California and Texas are sovereign states, and becoming a citizen of California is really just a matter of moving there. Acts and corporations of Texas are recognized as "foreign" in California. Citizens of California have to swear a loyalty oath to the state to work for it, and all able-bodied male citizens of California are members of the unorganized militia and are subject to the state code of military justice. Treason against California is punishable by death, as is treason against Texas (apart from treason against the US). Per the Tenth Amendment, the federal government has only the sovereignty granted to it by the states via the Constitution.

As a country, you can move almost anywhere in the US and have full citizenship rights. (Note that Puerto Rico, American Samoa, etc are not part of the US, and you don't get automatic rights when you move there. American Somoans are not even US citizens by birth, for example, because it's not part of the US. Palmyra Atoll and DC are the only part of the US not part of a state, and residents are not citizens of a state and don't have full US citizenship rights.)