We are clueless about how long things should take
How it often works:<p>Manager says I want an A that does B?  How long?<p>Most of the time estimate is N days, actual is N +/- 20%.<p>Sometimes it's N days, and you get lucky it's N/3.  Instead of credit, you now have a reputation of padding estimates.<p>Sometimes it's N days, and you go oops, and it's 10*N.  Now you are a slow incompetent.<p>This is why estimation is such a no-win for developers.<p>For areas that come closer like construction, they have centuries of prior experience and often the contractors are big enough to push back.<p>To use the example of this article, go to a boatyard, and say I want to 150 foot yacht with a hot tub and a 20 seat theater, and my budget is $10,000.  You would get laughed out of the office.