Recently new laws in the US mean that all people who arrive in the country have to be photocopied. Just the face and two fingers, but this is enough. I believe it is so that if you die due to an accident, scientists acting on behalf of lawyers can clone you from the images and your clone can sue.
But really it's an immigration thing. America, like a lot of countries - especially those created through immigration, is paranoid that they are going to be taken over by stealth. And when it happens, they will have a complete set of finger-prints of the new masters. Those without state-held finger-prints will obviously be the new underclass.
There is also a homeland security risk. Currently the fingerprints are just stored and not used or followed up. But in the future, they will compare the finger-prints with those who have committed previous suicide attacks. These people will not be let in.
Obviously, this hi-tech photo shoot takes it's toll on waiting times, but it looks like something is being done, which is what matters.