Why can’t the IT industry deliver large, faultless projects quickly as in other industries?

A interesting and insightful discussion emerged as to why the it industry can’t deliver large faultless projects quickly as in other industries that deal with other huge projects, such as Airbus or skyscrapers.
Read full discussion here : http://programmers.stackexchange.com/questions/158640/why-cant-the-it-industry-deliver-large-faultless-projects-quickly-as-in-other