Blame? What's that? The best you can hope for these days is:- "lessons will be learned"!
Anyway (in my experience, at least), common sense ain't that common.
But, how about this as a hypothesis
1) Too many "policies" from too many sources
2) Badly written and over-complicated (or even conflicting)
3) Too many "highly trained" folk who consider it beneath them to read "policies", anyway
You know the type:-
1) "Oh, I already know all that"
2) "I'm too busy to read all that" ... etc.
(usually whilst gazing into a computer screen - apparently surfing the 'net [one of their Human Rights, surely?], or fiddling about with some hand-held toy or other, engaged in a bit of "social media")
Dare I once again mention that old-fashioned word - discipline!