Why are builders afraid to have a 13th floor but book publishers aren’t afraid to have a Chapter 11?

I’m not a builder, yet I’ve seen several buildings with a 13th floor. And I’m not a book publisher but every book I’ve read had an 11th chapter in it.

Guess it all depends on how superstitious the builder/publisher is!

Can you come up with something INTELLIGENT to ask besides crazy math/science/history questions(I already graduated)?