To be perfectly honest, the fact that NSA already has access to every single packet into or out of the US (and probably most inside the states as well...) for much cheaper with much less rollout overhead, points me away from these types of algorithms as a "tool of mass surveillance". Think Occam's razor - you would need massive political pull to put this in every tiny jurisdiction, not to mention equipment maintenance and the massive attack vector exposed by hundreds of "internet of things" devices piping data to some endpoint. The recognition results would need to be geolocated, time tagged, and encrypted to NSA specs. To access the data it would have to go through some kind of unclass->classified firewall, get decrypted AND they would have to keep the public in the dark, blah blah blah.
The tools already revealed for large scale surveillance are cheaper, more effective, and more robust to outside attack than the mentioned ideas. More importantly, they are already there - there is no rollout cost at all! And up until recently it was also easier to keep the public in the dark...
I do see applications at the places you mention, but for a very different reason - border inspections (coupled with human oversight) are an excellent place for automation where a small amount of effort could lead to a massive increase in throughput per person.
The only downside is that officials who deploy these things will want guarantees on effectiveness, which you can never truly give due to statistics. Couple this with the fact that neural networks are very difficult to tune for false negatives and false positives and it would be a difficult sell.
One alternative would be to use these types of networks as black-box preprocessing, followed by a "tunable" algorithm like logistic regression where you could effectively control the ratio of false positives - a high rate of false positives coupled with human oversight could still lead to a large boost in human performance if most of the border inspection process is uninteresting.
But still there are unions... which is a whole separate issue to itself.
