Have you ever broken a speed limit? Speeding contributes to accidents in far higher proportion than anything else. (Google is your friend). If you've ever exceeded the limit, you're a damned hypocrite if you complain about bikers breaking the rules.
Breaking the speed limit by 5 MPH results in a fairly small increase in the odds of an accident being fatal. Speeding across an intersection on a bicycle without stopping greatly increases the risk of a fatal accident, from zero to 100% if you get hit.
Actually; at 30 km/h almost no accident is fatal, and at 50 km/h almost all of them are. Doing 5 mph (8 km/h) over a 24 mph (30 km/h) speedlimit will lead to a lot more more deaths statistically. Also getting hit by a car while speeding across and intersection is not a common way to have an accident as a cyclists, fatal accidents being even less common.
Traffic calming can mean so much so it's hard talking about it, there are as many bad examples as good, but a good thing is to lower the speed of cars because people survive low speed crashes pedestrians as cyclists.