Whenever I bicycle over an expressway, I notice that the expressway is in one of two conditions. Either it is in a traffic jam, or just about every motorist is breaking the speed limit law. (To paraphrase Andy Dreisch, motorists "are only out for the lawlessness of it.") A motor vehicle breaking the speed limit is a deadly weapon -- 2 tons of steel or more impacting at 70 or 80 miles per hour can be lethal.
If you are driving a car, the surest way to annoy the motorist behind you is to obey the law. If you go at or below the speed limit, the person behind you will get enraged because you are interfering with their ability to break the speed limit law.
While Critical Mass may not be for all cyclists, I find some of the criticisms of Critical Mass on this board to be puzzling. Motor vehicle culture is a culture of lawlessness - constant speed limit violations, constant violations of anti-cell phone laws, lying to police officers to try to get out of tickets, and DUI. So when a critic of CM says that a motorist will learn to hate all cyclists because of Critical Mass' "lawlessness", I'm left to wonder if the corrolary is true: will motorists learn to hate all other motorists because of the lawlessness of motorists? Are motorists' rights being set back by the 50,000 car fatalities per year? Will legislators move to restrict the use of motor vehicles on public roads?
If a motorist gets enraged when he is behind a group of bicycles, there's a good chance that the reason he is enraged is that the bicycles are getting in the way of him breaking the speed limit law.
A single SUV can break far more laws and be far more dangerous than 50 cyclists can. The SUV can break the speed limit law effortlessly whereas it's difficult for the group of cyclists to break the speed limit on many roads. An SUV driver can run down a cyclist off the road and kill them. A cyclist cannot run an SUV driver off the road and kill them.
If I were on an expressway with 800 cars, about 90% would be breaking the speed limit (assuming that there's no traffic jam) and the consequence of this lawless behavior can be to maim or kill people. On the other hand,I've been in Critical mass rides with 800 riders, and I've never seen more than maybe half a dozen riders being unruly. I don't condone their unruliness, but their behavior isn't going to maim or kill anyone.