Seriously? You do realize that we're talking about the capacity of the air vs land, not individual trains vs individual planes? Yes, a single train has more cap

Seriously? You do realize that we're talking about the capacity of the air vs land, not individual trains vs individual planes? Yes, a single train has more capacity than a single plane, but the limit to how many planes can be in the sky is more or less a function of how sophisticated your ATC system is. UK rail hit the physical limits a long time ago, and expanding it is extremely hard because the land is all taken. That's why HS2 is so expensive and slow, yet (was) still being pursued, because it's the only way to add meaningful capacity. Same with Crossrail.