[liotier]

Because they trade ugly surface volume occupation for being much cheaper. Flood resistance is a side-effect.

[em-bee]

for someone who loves trains, above ground rails are not ugly

[ant6n]

The trains aren't ugly, the concrete infrastructure is. (Note that elevated trains in the US often look much nicer because they use steel structures, something that isn't being built today).

[JCharante]

Roads are ugly too compared to a meadow. I'd rather have cars underground and human-powered vehicles and pedestrian only areas instead of roads.