If murder is bad because you're taking away the life that might've been lived by a third party, then one could argue that false incarceration is similarly grave

If murder is bad because you're taking away the life that might've been lived by a third party, then one could argue that false incarceration is similarly grave as murder. That being said, I don't agree with your premise. Facial search/recognition is just the first step of the investigation, identifying a pool of "possible leads". This is very similar to creating a list of people who were in the neighbourhood. Lots of false positives initially, but still a good place to start looking.