The whole story makes no sense. How do they perform evals without a full reasoning trace of how the result was achieved? And if they have a full trace why did

The whole story makes no sense. How do they perform evals without a full reasoning trace of how the result was achieved? And if they have a full trace why did it take so long to detect the bad behavior? I understand that they disabled the safety nets during testing but what does that have to do with not monitoring the activity.