When I was in Argentina last week I was in line at passport control and they were showing a video on the new digital DNI (national id card that all Argentineans must have) being changed to a digital record of your fingerprints and face scan. They were selling it as a way to prevent terrorists and to be convenient, which perhaps it is. It also gives the government much greater ways to track and control people. "Hermano Grande" (Big Brother) would be proud! (Edit: I have since found this article on the topic)
For example street CC video cameras (of which for example there are 4 million in London - I don't know how many in Buena Aires) can be tied to the face scan to know where you are at all times. People in protests against the government can be identified without arrest and penalized immediately without trial. Entering buildings that require scanning will track were you go too. And if you are "naughty" then forget about being able to enter those buildings which might include not just government services but bank ATM, gas stations and supermarkets. If food rationing occurs in a crisis then you can only get government food if you are "good".
What a great way to control a populations. Now to be clear it is only the digital DNI that I am aware of right now but there is so much opportunity for abuse with this kind of system that I would be concerned if I lived in Argentina or any other county that does this.
PS The US already face scans and fingerprints all foreigners who enter the US - currently over 70 million records are held by the DHS. So don't think that this won't come here. It already is and I predicat that the next big terrorist incident will make this system be extended to US citizens.