There was a nasty stamping incident in the England v Ireland match which resulted in no action on the field - did neither the ref or touch judges see anything?
The short answer to that, imho, is no. That is why, again imo, citing is beneficial.
More broadly, I don't think refs in rugby bottle decisions any more than they do (or don't) in football. I think their decisions in both codes are variable and matters of judgement. And sometimes they simply get it wrong. Yes, those decisions can cost clubs big time but as hard as that is for clubs to stomach, I don't think the referees can be blamed.
None of that is to say that referees shouldn't be assessed and trained as necessary, nor that assistance (in the form of technology etc) should not be explored, but that ultimately it will come down to everyone accepting that any decision, no matter how it is derived, is fallible and simply accepting that.