Buildings certainly do change. I just finished 3 months of work on a structure that was "finished" 20 years ago. We had the client coming to us with changes t

Buildings certainly do change. I just finished 3 months of work on a structure that was "finished" 20 years ago. We had the client coming to us with changes to our changes several times a week. The problem with software is that we don't build it in a way that makes changes easy (or at least not all the types of changes that clients frequently want to do), and we do a terrible job of communicating the costs of changes. Give me any program, and I can change a couple words in its requirements which would cause more than half of its lines to need to be changed. That's just how we write software today. (We diligently made 'time_t' a typedef, and then we embedded the physical size of it in every file format and API and protocol so we can't actually change it without breaking everything.) Maybe we need a new type of specification system, to encode the distinction between "this is a decision which is immensely expensive to change and will necessitate rewriting half the program" and "this is just part of the facade and we can change it cheaply at any time".