If the system worked as you propose, but regularly glitches, it would show someone's picture when it glitched. The check-in staff wouldn't see anything weird ab

If the system worked as you propose, but regularly glitches, it would show someone's picture when it glitched. The check-in staff wouldn't see anything weird about this particular person's photo: he's not otherwise noteworthy. Maybe it would be the person with the seat number from a previous flight. The attendant assumed it was a glitch because it usually is a glitch. The official policy is that there are no glitches and that the staff member should have called security and investigated the plane. The actual policy from middle management is "if you do this you will end up calling security 30 times a day because our systems suck and half our flights would be delayed, so just use your judgment until the technical issue is fixed". Here they really do need a technical solution to a technical problem. Improve the tech so it has false positives on less than say 0.1% of flights. Then you can enforce the official policy and discipline staff members and/or their managers if they don't follow it.