It's like an MOT though, the signature only verifies that an inspection was passed at such and such a date, after that its meaningless also I suspect the Unions will not let their "Members" take any blame.
Of the three stretcher bars two were fractured, one was not in position, and there were missing bolts. One of the stretcher bars was possibly fractured before the accident and one possibly after it. It looks as though a recent planned maintenance inspection was not carried out, and if that's the case it's clear that an individual or individuals have been negligent, and may be charged with criminal offences.
If "those at the lowest level" are shown to have been at fault then I hope they do get the blame. Are you suggesting that someone else should carry the can for their shortcomings?