…yeah I know you did not ask!
I do not know if this inability to observe and learn or an overestimation of one’s driving abilities and reaction times. 
According to the State Farm website a safe following distance is the 3 second rule, 4 seconds is better. That is when the car in front of you passes an object start counting. You should be up to at least 3 before you pass the same object. Rush hour traffic in St. Louis moves between 0 and 80 mph. I try to get no closer than 2 seconds. Primary because at 62 going on 69 I know my reaction times are not what they were. Even at this separation, I have folks pulling in front of me all the time, or trying to whip around me because I am going too slow. Never mind that I maintain a constant separation with the vehicle ahead.
The percentage of all accidents that are rear-end collisions (termed a shunt in UK) is between 23 and 30%. I drive 50 plus miles round trip commuting from Chesterfield to downtown St. Louis. I almost never have a round trip without seeing at least one accident. Frequently I see multiple accidents, and the accidents frequently involve more than two cars. My estimation of the rush hour traffic accidents being rear-end collisions is in the high 90s. Rear-end collisions are almost always caused by following too close.
Let’s get back to my opening statement. I would think if you see this type of accident repeatedly happening a bell would go off somewhere. I will vouch that it does not. Tailgating is an awful problem in St. Louis rush hour traffic. Maybe there is a reason humanity keeps repeating the same mistakes over and over, century after century. Meanwhile I will maintain my 2 second separation and if you get too close to my bumper I will start slowing down.