Yep, that's exactly it. Traditional (meat-space) engineering has a clearer delineation between design and build (and whatever other phase you want to include).

Yep, that's exactly it. Traditional (meat-space) engineering has a clearer delineation between design and build (and whatever other phase you want to include). We can see this in estimating bigger infrastructure projects (where there's an end-to-end estimate of time and budget) - at least in the US, these almost always miss as well. But, building a housing development (once permitting/zoning is done) has a much higher likelihood of being close to estimates. Building a spec house is a "solved" problem. Similarly, if a software team is building a pile of CRUD APIs with a basic web frontend, in a domain they have experience, they should be able to estimate that pretty well.