I’m with you. It’s frustrating that these things haven’t been exhaustively analyzed, just because the current civilization is about 14 centuries in the past.
I’m not a UN fan, but having the UN declare these to be somehow legally separate from the government of the country may head towards better access. Until something like that happens, scientists will be at the mercy of corrupt local folks.
I'd call out for the elimination of corruption in Egypt, but that would require the elimination of Egypt. ;^)