I understand that but the camera was an item of very significant importance from a practical as well as an historical perspective. It would be nice to think that the people in charge would have asked about it instead of supposing or assuming. Maybe the problem is that everyone thought someone else had looked into it, so nobody looked into it. In the gubermint that’s often the case.
Probably everything aboard the lander was “surveyed” (written off the books as lost) before the launch. In a high-risk mission (such as the Normandy landings), that’s not unusual. Also, the lander itself was not coming back, so perhaps they assumed that any part of it not already on a checklist (like film cartridges) would be left behind as well.
And it may be for the best that the camera didn’t surface until now...people have been incredibly careless with historic items, soon after the fact. The original videotape of the first moon landing was lost, stolen or taped over along the way...what survives now is more akin to a kinescope (recording of a TV screen image) rather than a copy of the original video.