Yeah, that's messenger work.
Rightfully, if you are run down and it's the driver's 'fault' the responding police should just play it straight and give the ticket to the driver, regardless of your job or if you were running lights all year long. Realistically, it doesn't always work that way. Police are likely to be sympathetic to the driver in the situation, even if you are just a regular civilian bicyclist. If they know you are a messenger they are likely to be even more sympathetic to the driver, and many cops will find it all but impossible to ticket the driver instead of you.
One veteran messenger I know was comatized by an SUV when its driver ran a light. The driver ran from the scene, abandoning his vehicle. The police officer who wrote up the report exonerated the driver for the collision, by claiming that the messenger was headed the wrong way on the one-way street. This was obviously a lie, or perhaps a blatant mistake, given the location of the impact on the vehicle, and the destination/start point of the messenger. The driver got a ticket for fleeing the scene, but that's it. If it had been a pedestrian he ran down, he'd probably be in jail right now.
How long have you been a messenger? Where do you work?
Think about these things all the time while you're working. You're damned if you do, and damned if you don't. If someone runs you over and knocks you out, nobody will be there to tell your side of the story. The cops probably won't care, the paramedics might not either. They might even think to themselves (as will some of the knee-jerkers on forums like this one) this guy got what he deserved, even if you've been riding safe for 20 years.
In fact, I would say the same thing to those out there who like to dress like messengers, use messenger bags and other equipment associated with messengers, and don't mind being mistaken for messengers. It's serious business, what you're doing. You're putting yourself behind the 8-ball for some fashion points.
When I was involved in a violent collision years ago, I picked my bloody body and broken bike off the street and then waved down a cop who happened to be driving by. Lucky for me, this guy was a true professional. Totally by the book, and no nonsense about me being a messenger. He even laughed out loud at the driver's claim that I was riding too fast and other silly excuses. This cop was Gary Whitman, the Chief of Police for the city of Denver. It usually doesn't work out that way.
It's tricky to say the least, to have to work outside the law in order to complete our required tasks, and then to rely on the law when the s. hits the f.