I heard there is a principle of face-to-face contact even if you have spoken with the missing person.

Even if the police speak with a missing person on the phone and the person says,
"I'm safe, so please don't tell the reporter,"
according to the actual manual, the police must locate the missing person and
meet them face-to-face.
This is because there are various variables, such as the possibility that
they have been kidnapped and a criminal is threatening them nearby.
Of course, if they did this every time, the police workload would be unmanageable.
Anyway, this Jeju incident is a case where a loophole in the system has been revealed.
It makes no sense that the case was closed simply because they spoke on the phone,
and it's truly concerning that even that closure could be handled by a single officer
without any verification system in place...