the theory is that is all the time needed to react to the person that is slowing/stopping, and that all cars can decelerate at the same speed.
Mammon slept. And the beast reborn spread over the earth and its numbers
grew legion. And they proclaimed the times and sacrificed crops unto the
fire, with the cunning of foxes. And they built a new world in their own
image as promised by the
sacred words, and spoke
of the beast with their children. Mammon awoke, and lo! it was
naught but a follower.
from The Book of Mozilla, 11:9
(10th Edition)