Oh, yes, on a couple of occasions I saw cyclists who were being plowed in by a car, with a driver looking the other way, who were completely silent because their forefront instincts were to be polite. I both case, the bikes were destroyed. One rider ended up in ER and convalesced for some months, while the other escaped with bruises. Forefront politeness instinct can be surely deadly. I keep horns to increase my chances of surviving - maybe I have ridden for too long in the streets.