... Perhaps because whoever was remiss either realised immediately what they had not done/done wrong and, without guidance from others, would be very unlikely to repeat the mistake, or that their senior/more experienced and widely-knowledgeable colleagues, probably close at hand, were practical people, understanding the whole operating environment and what had gone wrong, and keen to make sure that the right way became understood a.s.a.p.sandwhich wrote: " ... Yes in years gone by, no names no packdrill, many yard derailments were soon dealt with, how should we say, very quietly and no questions asked. different world now. "
My feeling is that the nowaday 'legal' separation of the parties and their 'interests', which together (not always amicably) constitute the national network, the operating compartmentalisation of its working, and any obligations to meticulously record all for both 'lessons-learnable'* distribution & in case of later come-back, seem to make the frequent, more onerous and long-winded formalisation of investigating incidents unavoidable, if the investigators are to come to understand what happened (particularly in certain methods/details of working with which such individuals are these days much more likely to be unfamiliar), and reach hopefully correct, fully recordable, conclusions and recommendations.
* - (I do not say "lessons learned" as that might imply that they always are, being absorbed fully into future practice, which, in a wide sense, I think, does not always happen when pressures to get the 'now' job done preclude background/retrospective research/reading.)