That is, software is trivially copy-able, so there is no reason to spend effort duplicating any software that already exists. (Legal reasons and "not-invented-here" syndrome notwithstanding.) This is a huge different from how the "real" world works, where almost all of the work involved in building, say, a car, is actually just the work of assembling identical copies of that product so that it can be physically sold to more than one person.
The insane amounts of repeated effort involved in building any physical product at scale have a silver lining, in that the repetition enables a very good and stable estimate of how long another repetition will take. Software is the opposite situation --- we only need to build anything once, but not having built that thing before, we don't really know how long it will take.