A huge percentage of motorists flaunt the law every single day. They fail to signal, they fail to yield when they're supposed to, they blow through red lights, they exceed the speed limit, they drink and drive. Sometimes these behaviors are so common that they acquire nicknames, like the "boston left". But we accept all this lawlessness as normal, as the fuzziness around the edges of lawfulness. Even though this sort of behavior is so common and so dangerous that it is responsible for the death of tens of thousands of people every year in the US alone and countless billions in economic losses in damages and injuries.

In contrast to that, bicyclist lawlessness doesn't even rate. But bicycle lawlessness hasn't been folded into the accepted comfortable fuzzy border around lawfulness so every instance is a horrid and unique crime against the sanctity of the law and the foundations of civil society.

Edit: both bicyclist and motorist lawlessness is problematic. But the existence of either does not somehow damn the entire population of bicyclists or motorists. There are good motorists and bad motorists as there are good cyclists and bad cyclists. As mentioned above, folks who rail against the universal lawlessness of cyclists are focusing on one of the least serious dangers on the road.