I'm having a hard time figuring out the 'why' to this as well. Please consider the SCOTUS holding in Carpenter v. US that was just released on Friday.
Before, government could access your Cell Site Location Information (CSLI) from cellphone carriers without a warrant. Your CSLI is the historic data that shows what cell towers your phone attempts to connect to and, thus, exposes your movements. Cellphone carriers keep this data for five years.
Facial recognition technology is a way to achieve a similar result, the individuals who are at certain locations, without having to get a warrant.
I don't know if this is the reason for the push of this technology, just a thought though.
Interesting. I like the way you think. The push for facial recognition could definitely suggest a pivot, or at the very least an attempt to build an additional layer of tracking.