The chart isn’t about high-speed rail. High-speed lines often actually have lower capacity than lower-speed rail. For one, many suburban trains are bilevel, which can almost double the capacity per train, whereas high-speed lines often aren’t bilevel. Further, the higher speed doesn’t actually mean you can move more passengers per direction per hour; you’re still limited by how frequently you can run trains, as you need safe stopping distance between each train. Thus, high-speed rail can run faster, but it also needs much more space between trains. Typically the highest frequency train/metro routes can run trains every minute or two. A 2000-person capacity train every 2 minutes is equivalent to 60k passengers per direction per hour.