In transportation there is almost always conflict, or at least the potential for conflict. Even on the most deserted road there are times when one person will want to go faster than the person in front. We have systems for resolving these conflicts: traffic laws, traffic cops, traffic signals.
But these systems are never followed 100% of the time. There are people who feel that the laws are wrong, or that the laws don't apply to them, or that the laws don't apply in a particular case, or that a particular law applies in a case when it actually doesn't. Enforcement is never 100%, and in many cities is far less.
When people aren't following the laws, they resolve conflicts with games of power and cunning. Sometimes one person will defer to another, giving up the transportation advantage for moral rewards. Sometimes a faster or more agile driver will slip into a place in line or a parking space and simply block the other vehicle from getting it.
Many times the conflict is played out in contests of weight and nerve in addition to speed and morals. In games of tailgating and chicken, a more brazen driver, often with a larger vehicle, will charge at another vehicle. The driver gives no hint that he or she is prepared to stop, leaving the impression that a collision will result if the other vehicle doesn't get out of the way. Honking the horn can be used for added intimidation.
When a challenge of chicken or tailgating is issued, the other driver may yield immediately, moving out of the way. The driver also has the option of ignoring the challenge and continuing on their path at the same speed. They may also answer the challenge, honking their horn in return and either speeding up for chicken or slamming on the brakes for tailgating.
If the second driver does not back down, the first driver faces the same choice: back down, continue or escalate. this continues until one party backs down or a crash ensues.
In such a system, pedestrians and cyclists have several disadvantages. In space-grabbing games, we take up only a small fraction of the space that a car or truck can occupy. In tailgating games, we usually go slower than motor vehicles. But it's in games of chicken that we have the worst disadvantages.
We don't usually have loud horns. I've fantasized about buying a portable air horn, but I think without backing it up with a large vehicle I'd be asking for trouble. We don't have speed, but most importantly we don't have mass and we don't have armor. If we lose a game of chicken with a car or truck, we usually pay with our lives.
The scariest thing, and a significant factor in cyclist and pedestrian injuries and deaths, is that many drivers play chicken with us anyway. They aim heavy vehicles at us at high speeds, as though we were protected by two-ton cars. Some of them are psychopaths who are well aware of our greater vulnerability, but after some uncomfortably close observation I'm convinced that the majority are simply acting out of habit and treating us like cars.
If you treat pedestrians and cyclists as cars, you wind up thinking that it's okay to charge at us. The worst you're likely to do is dent my fender, right? Of course the reality is that you can do much, much worse, as people do every day. For those of us who are still in touch with reality it has a chilling effect, which is why you see so few pedestrians and cyclists on stroads.