It would seem that, at least in relation to electrical matters, it can sometimes be far more "tedious and fraught" than most people would regard as 'being worth the effort'.I suppose but again its so vastly unlikely and I suspect just an urban myth...BCO's are not a law unto themselves, you have the right of appeal and having had it with foundations and drains its not at all tedious or fraught.. ....
One of the issues is that the BCOs themselves very rarely have any electrical expertise (or necessarily expertise in other fields about which they may be deliberating), so they can tend to play things by what they regard as "the book" - which (on the basis of what we see here) will often demand compliance with 'guidance' given in Approved Documents, even when it can be argued (if one has enough inclination and stamina!) that one has satisfied the actual requirement of the Building Regs themselves.
A seemingly common, albeit fairly trivial, example of this is a BCO's demand that mechanical ventilator fans are fitted (as suggested by Approved Doc F), whereas all that Part F of the Building Regs actually requires is that "there should be adequate ventilation provided for people in the building". In such a 'trivial' case, I think most people would probably 'give in' to this demand and fit the fan(s), rather than expend time and effort in attempting to challenge the demand.
Kind Regards, John