The prime directive of any government -- any government -- is to prevent its own demise and extend its own reach and influence. What interferes with this is not things like terrorists, but ordinary people with different ideas about how the world would be a better place with more minimalist government. Cynically viewed, government says: "These people who think differently need to be stopped, crimes found against them, etc. But how can we know what they are doing unless we can track where they are travelling. Ahh, at the first opportunity let's install an RFID tracking system. It can be justified as 'in the national interest' and 'to combat terrorism'."