I take issue with this graphic. It is disingenuous to imply that foot traffic isn't the highest density form of transit. You can't load a train with other trains. People have to walk.
You forgot to account speed. Trains go something between 20-40+ times (or far more if you account carriage) faster than average person walking. This increases the throughput of the lane massively.
Odd take. You don't load trains from the front, you load them from the side. A suburban rail lets you turn ~5 3.5m wide "lanes" of pedestrian traffic into a single equivalent lane of rail.