Sometimes running the red is the SAFEST thing to do. This is particularly the case in cities that are unapologetically designed for automobiles, with no accommodations for cyclists.
For instance, it is quite common for cars to turn right, without signalling or even seeing the cyclist immediately to their right. If I’m stopped at a light, and I get an inkling that the car to the left of me (a) is turning right and (b) doesn’t see me, then the safest place for me to be is anywhere *but *immediately to the right of that car. So if I get the chance to proceed safely through the intersection before the light turns green, that is the best option for me.
There is another situation I’ve described here before, a roundabout where the bike lane basically ends abruptly, and any cyclist on it for the first time is involuntarily channeled south. If you want to go in any other direction (e.g. proceed southeast like the automobiles do, or proceed east like the (unmarked) bike route expects you to do), you have to do something that is some permutation of illegal and dangerous. (The legal thing is actually quite safe, but drivers don’t know that it is legal or safe, so it usually involves nervous drivers and often some honking and fist-waving, which makes it not so safe. We don’t have a lot of roundabouts in these parts, so people don’t know how to work them.)
There is a stoplight a few hundred feet ahead of this roundabout. If I am stopped at that light and I get the opportunity, damned right I’m going to proceed, because if I’m going to have to be doing something potentially unsafe (and unpredictable to drivers who aren’t thinking about cyclists and roundabouts), I want to be doing it when the road is clear and everyone can see me. If I proceed through the first light at the same time as the cars, it will make it far more dangerous for me to go anywhere but south when I get to the roundabout.
(As evidence I offer the measurable fact that honking and cursing never occurs when I run the red, but regularly does when I proceed at the same time as the cars.)
(There are also those fun intersections where the light only changes in your favor if a car drives over the pressure pad or a pedestrian presses the button. So you can wait for a car or a pedestrian, or you can dismount and press the button, or you can run the red light. This of course is a matter of convenience, not safety, but it is frustrating to be subjected to absurd inconveniences like this simply because of your chosen mode of transportation.)
With the exception of morons, nobody is a better judge of what is safe than the person whose life is actually at stake (i.e. the one not encased by a steel cage). There are times when something might appear from the comfort of your car to be unsafe, that might actually be the safest option for the cyclist.
Of course, there will always be moron cyclists who don’t know what’s best for themselves.
But overall, cyclists are at far more risk from drivers than vice versa, and we’re just trying to get where we’re going, just like you are. Next time you get pissed off by a cyclist, please cut her a little slack, and imagine how much longer your commute would take if all those cyclists were in cars.