Why not? If an American moves to Europe, in most countries your gig back in the states will be treated as a self employment,at least from taxman's perspective.

Why not? If an American moves to Europe, in most countries your gig back in the states will be treated as a self employment,at least from taxman's perspective. Even within European Union the legislation around intercounty employment is such a grey area that the easiest,and often the only way, is to be self employed.