Because the layperson I'm talking about can't think in terms of abstractions, kind of like a math student who hasn't learned algebra yet. They can only verify t

Because the layperson I'm talking about can't think in terms of abstractions, kind of like a math student who hasn't learned algebra yet. They can only verify the correctness of their algorithm by inspecting the intermediate values at every step, and scrolling down through the input set to inspect the corner cases. The problems with this approach are extremely obvious (which is why spreadsheets error out so often, or even worse, produce the wrong answer without any visible errors), but in many cases this is the only way for the people with the domain knowledge of what needs to be done to build an application to meet their need (they don't know how to code and they don't know how to write a functional spec).