fun fact. modern planes consume ~3-4l per 100 passengers per km or 3-4l per passenger per 100km.
efficient ICE cars consume ~6l per passenger per 100km.
add to that, that there's basically no good alternative to fast very long distance or cross-continent transport
and even if you do, the tree works by not having ANY air in them so as soon as there's even the slightest amount of it, the tube wont work anymore