Just a view... on my commute, the most considerate, road-aware drivers are the ones in HGVs. I can understand that there's some frustration across most road users with other groups, but the people driving the big wagons seem to be the ones with most sense of responsibility. This says everything about the importance of the "perception of danger" these people have, and sheer ignorance of this by certain other groups, including some who drive for a living....
Also I think that cycling does need to take a little bit of a look at itself when it comes to group riding, from my experience - for instance, on the weekend at the Forest of Dean sportive where there were times when the bunching and line-crossing was clearly (and perhaps understandably) getting on the locals' nerves. Nothing serious, but then again it all contributes to a perception which comes up in such forums.