4) A house, e.g. "3 beds, 2 baths, timber frame" is a much more known quantity with standard tools and techniques that have been executed many many times before

4) A house, e.g. "3 beds, 2 baths, timber frame" is a much more known quantity with standard tools and techniques that have been executed many many times before, than a typical software project. The house builder can average the last 100 times that spec has been executed. The software project cannot. It is inherently much more variable and speculative. It's not entirely to do with "blame the people" ideas such as "no culture of estimation" and "little direct incentive". The nature of the project and the way to go about is simply much more wide open. And doesn't have such easily-defined endpoints.