Yes, this is not a 'one person' mistake, but a 'whole systems' failure. In fact, many systems.
He was apparently trying to get back in. An opportunity there and then for the error to be rectified.
He doesn't appear to be running away, or trying to hide. Plenty of CCTV coverage.
Stated upthread that this is not the first time a wrong release has happened. And so, you would expect protocols to be in place, to correct this asap. Nothing.
Because of the heightened coverage, things should now change and improve.
'Bought in' temporary workers, probably covering for staff absences , would not get the same amount of training as new recruits. Not worth the investment. Happens in lots of situations.