Except nobody with a sane mind would consider this an acceptable safety system. It's widely known humans are not capable of performing this job. Period. Everywhere else, where there's a need for long stretches of uninterrupted human focus, you have systems on top of systems ensuring this happens.

In swimming pools, you have lifeguards with <30 minutes shifts, overlapping coverage zones, and managers hovering behind them to ensure they do pay attention. On trains, you have dead-man switches that stop the train if the driver isn't paying attention. The military gives pilots amphetamines if they need to stay awake for long hours. Etc.

You just cannot expect a person to stay focused monitoring something for more than couple minutes. You need to have systems to help them and mitigate the unavoidable lapse in focus. At the very least, they should've taken away her phone and made her narrate what she sees on record, while making her aware it will be reviewed and compared against video recordings afterwards.

They set her up to fail, so it's wise to ask what her role really was. Convenient scapegoat, organizational surge circuit breaker, ablative armor - it's a plausible explanation.