I thought software were learning how to commit crimes. Isn't it a bit of a stretch to say that the non-criminal pictures are "smiling"? It seems more the difference between relaxed lips versus a "proto-smile" lip tightness, with only some light tension of the muscles around the lips, without significant action of those that pull the lips and the mouth edges upward and outward, and open the mouth, showing teeth. But I guess it can still be called a detection of subtle expression nevertheless.