I have ridden an early morning weekend ride once, where I encountered a driver who was under the influence. Luckily, I came up on him, and recognized his erratic behavior, swerving, etc. I backed off and took another route. What if he had run the red light at an intersection and plowed into a large group illegally crossing? Sure, most of the drivers in the areas may be okay with the groups running the lights, but I will never be okay with risking my life over it and rolling the dice against that one driver we never think to encounter.
Riding is a passion & a hobby of mine, not a career. It does not support my family or bring me any economic gain. With that being said, I stop at all stop signs, red lights, etc. when riding solo or with a group. I can't recall ever being in a group that ran a red light or a stop sign. Sure, there are splits at times, but the "stopped" group just has to work harder to catch back up. I always leave my house telling myself I will do everything in my power to come back safely. Obeying traffic laws is a must for me. But hey, that's just me.