[walrus1066]

Indeed, I've never in my career (in high level businesses, I.e. Finance, advertising) seen such a thing as a proper 'specification'.

It's more the business has a high level, rough idea of a change/feature to improve the business, and we figure out together the exact details, some of which surface during implementation, and then verify it gradually in the wild.

We could have spent x10 time instead drawing up a formal spec up front, but it would have so many assumptions baked in, that it'd get invalidated in the wild anyway.

[craftinator]

So the people designing the spec don't have enough information about the problem space. As the programmers begin working, they explore the problem space, extract the information they need to understand a solution, and then they can actually solve it. Bit of a Schrodinger's cat situation... The solution must remain undefined until observed.