Great points! Very few of us have photographic memories, particularly when at the time there’s no known reason to try to memorize a person’s facial features.
A bit on the topic of sketches -
“Forensic artists who have drawn their fair share of facial composites will probably confess an awkward truth about police sketches: They aren't very accurate. By one estimate, hand-drawn composites by trained artists are roughly 9 percent accurate in terms of producing a recognizable likeness to a suspect [source:
Avril]. And as we mentioned previously, computer-generated composites statistically tend to be of even poorer quality than hand-drawn sketches, with around 5 percent accuracy [source:
Avril]....
......Forensic artists argue that the role of police sketches isn't to construct a perfect portrait of the perpetrator. The point of police sketches is to publicize crimes, attract leading clues and get the public looking out for suspicious persons [source:
Lichtman]. That's why the artists will highlight standout features -- a
tattoo, scar, facial hair -- that might jump out at passersby.”
How Police Sketches Work