Speed and Danger
Speed and Danger
[A two-axis diagram with two double headed arrows centered in the middle of the panel. Each arrow is labeled. There are four large dots in the diagram, three close together in the top left corner and one in the bottom right corner. Each dot is labeled.]
[Y axis:] Top: Crashes are safe Bottom: Crashes are dangerous
[X axis:] Left: Slow Right: Fast
[Dots from top left to bottom right:] Normal sports NASCAR Formula One Rocket launches

In this scatter plot Randall plots the speed of several vehicles (including people on foot for "normal sports") and how disastrous a crash would be. The punchline is that space rockets travel so dangerously fast, and crashes are so utterly catastrophic, that it pushes literally every other kind of crash to the "slow and safe" corner by comparison. (A similar punchline was used in the title text of 388: Fuck Grapefruit .)
With the plot Randall makes the observation that the danger of a crash is greatly influenced by its speed and highlights the concept of relativity between what we perceive as "fast," normal sports and two different types of racing cars, vs. a much faster vehicle, a rocket during launch. A rocket may appear to ascend slowly (and of course it begins its ascent slowly), but on the way to orbit it ends up moving very fast. But before it reaches the more extreme speed regime it will be far away from the ground (and the casual observer), where there is nothing to compare this speed to as opposed to a race car speeding by a spectator during a race.
Apart from the high speed, there is also the altitude to take into account for a rocket launch, and the vast amount of fuel needed to get into orbit, and any sort of catastrophic failure is almost certainly fatal ( Apollo 13 notwithstanding).
Racing cars are often involved in crashes, but at that speed it is possible to construct them so even serious crashes may not be fatal. Although rockets are also made as safe as possible, it is a completely different regime of speed and danger , and the risk of something going wrong during a take off is much higher, and it is impossible to prevent a lethal disaster if the launch fails during the ascent. This results in a much higher mortality rate for each crashed rocket (probably 100%) vs. crashed sports/race cars.
Rocket launches are compared to "normal sports " (presumably meaning people running approximately 25 km/h, and possibly also polo horses galloping approximately 40 km/h), NASCAR (which reaches speed of 320 km/h), and Formula One (F1), where the fastest race cars go 380 km/h. Although peak speed for an F1 car is higher than NASCAR, the average lap speed is much lower as F1 tracks have slow corners while NASCAR ovals can be negotiated with much less speed variation. It is also arguable whether F1 is more dangerous than NASCAR - there have been fewer fatalities in F1 this millennium, though fewer cars compete and races are of shorter duration. The 2016 Formula one season had 21 races, with each race lasting 1.5~3 hours. The NASCAR season had 36 races, with each race lasting 3~5 hours.
A rocket launched to reach the ISS needs to match the speed of the space station which moves at 27,600 km/h. A rocket that needs to escape from Earth needs to reach 40,270 km/h, but so far no humans have escaped. However, the astronauts going to the Moon came close, with Apollo 10 setting the speed record for manned flights with 39,896 km/h. (It was only about 0.4% faster than the next 7 missions that, in contrast to Apollo 10, were supposed to land on the Moon). The lowest of the rocket speeds mentioned above  is still more than 70 times as fast as the highest speed for race cars.
The title text serves to emphasize the point further, as an astronaut (used to the several G's of acceleration during takeoff and overall much higher speeds) would likely find a NASCAR car moving at ~300 km/h paltry compared to what they're acclimated to and has supposedly aggravated NASCAR drivers by making a point of saying so. And thus this is used to explain why there are no passenger seats in NASCAR cars, to prevent astronauts from joining the drivers for a nice, slow ride.
Of the many charts in xkcd this one is notable for containing the fewest sample points of any scatter plots in xkcd.
[A two-axis diagram with two double headed arrows centered in the middle of the panel. Each arrow is labeled. There are four large dots in the diagram, three close together in the top left corner and one in the bottom right corner. Each dot is labeled.]
[Y axis:] Top: Crashes are safe Bottom: Crashes are dangerous
[X axis:] Left: Slow Right: Fast
[Dots from top left to bottom right:] Normal sports NASCAR Formula One Rocket launches
