It’s not the kind of search where they need to be very precise; certainly not pinpoint accuracy. t’s just another tool to narrow their searches that rely on other details.

And if you’re a fully grown adult, not undergoing radical facial reconstruction, it seems unlikely to be that the relative distances and orientations of your eyes, nose, and mouth are going to change very much. My driver’s license photo is at least a decade old and even though my face looks different on the surface due to age, changes in weight, and changes in hair color and length I’d bet my key features are still in relatively the same places.

Of course they could also be using this for more sinister purposes. No argument there.