This is the prisoner's dilemma. If you slow down and drive smoothly, and everyone else does too, then everyone benefits greatly. But if you cut in front of one

This is the prisoner's dilemma. If you slow down and drive smoothly, and everyone else does too, then everyone benefits greatly. But if you cut in front of one of the smooth drivers, which you can since he's leaving lots of space, you benefit personally by gaining a car length while inconveniencing everyone else in that particular lane. Well, at least until the guy behind you has smoothed out the difference. Human nature makes smoothing out traffic an improbable solution.