Turning privatized interests into voluntary cooperative ones presupposes individual ownership of the means of production, which also requires that individuals have the ability to exclude others from utilizing their owned means of production. That seems to be something that gets lost in translation a lot, I've noticed. Communism and socialism cannot be voluntary; if they are voluntary, by definition they cannot be communism or socialism, as both of them preclude individuals from excluding others from their property.
RE: Open Borders vs. Closed Borders: A Market Anarchist Perspective