One of my favorite shows is Grand Designs.
Building a house is probably the most understood human activities; as you stated, you can take a standard design on a normal building lot and throw up a house in a very predictable amount of time. If you've done it enough, you can write down a schedule of when every piece of material and every trade needs to be on site.
Grand Designs always involves some combination of unusual design, unusual sites, and unusual techniques, and frequently inexperienced builders. People set out to accomplish something grand, and usually succeed, but it takes much longer and more money than expected, and especially more than constructing a conventional house on a conventional lot.
Now, besides echoing your point that many novel software projects are much more akin to a Grand Designs house than a cookie cutter ranch in a Midwestern suburb, in Grand Designs one concept that is proved true time and again is that once you are out of the ground -- once you have your foundation in, your gas and water and sewer and electric hookups -- the hard part is over and the job will proceed much more smoothly. It's hard to estimate before you get out of the ground, because the ground is filled with unknowns and unforseen problems. You might still misjudge how long it will take you to finish, particularly the finicky details that always take forever, but this is purely a failure of estimation; an experienced builder could predict the time to spackle, trim, paint, install flooring and built-ins accurately, you just didn't realize it. But under the ground, there are all sorts of problems with rocks and water tables and pipes and whatnot you can't predict.
Do we, as software engineers, have a similar inflection point in our software development? Do we ever get "out of the ground", to the point that most of the unknowns are known and we have a predictable (if still great and difficult) amount of work remaining?