"Free" Immigration & "Free" Trade Parallels

I see parallels between the problems of immigration in a world of state borders and international exchange in a world of state-managed trade agreements. NAFTA is 2,000 pages long and is riddled with subsidies and tariffs and sweetheart deals and byzantine regulations. Yet both paleo-conservatives like Pat Buchanan and left-libertarians like Nick Gillespie call it a free-trade agreement. Go figure.