As a driver who covers over 40k per year I see many acts of stupidity every day, from pedestrians, cyclists , horse riders, bikers , truckers you get the picture. The standard of personal responsibility and common sense has gone so far down that the authorities keep lowering speed limits and have made anyone who wants to overtake a criminal in many peoples eyes. In the Westfield I often overtake multiple vehicles as they bunch together and do often close up to protect their space when they see others who are willing to overtake.
With bikes I use my mirrors and if I am in a que of traffic moving slower than the bike wants to go, I indicate to the right and move over so they can undertake, better to have them in front of me than sat on my bumper and I almost always get a foot wave in return.
Too many think that you have offended their person if you overtake, it never bothers me getting stressed is a quick way to ill health and arguments, life is too short