Lots of names and words dont make sense if you think about them too much. Why is a fender of a car called a wing or the trunk a boot? (they were the names now used in the USA first before we changed them). Why is the district line so called. I drove past a high density housing project today that is being knocked down to be replaced by another slightly different high density housing project with modern hi-rise blocks. The name? Kidbrooke Village. It's about as far removed from being an actual village as humanly possible.

People call the underground lots of different names. The tube, underground, metro, etc. You cant stop it, they will call it what they call it.