I think part of the reason is just that they aren’t frequently replaced (I think it is often a very annoying place to install new escalators). Personally I pre

I think part of the reason is just that they aren’t frequently replaced (I think it is often a very annoying place to install new escalators). Personally I prefer to manually climb the stairs and I’m often surprised by how much space there is between escalators (it often seems like 50% of the width of a tunnel is just metal closing up the space between the parts of the escalators you can stand on) but I think my opinion is rare and it would be inefficient to have a flight of stairs that nearly nobody uses.