A material is not always the same material, that's a non-trivial part of what engineering is about managing. Building to code is downstream of engineering, and that's more or less when you can get away with “SPF is SPF”, because the building code is already accounting for the differences in the safety margins and allowed/required techniques, vs the non-trivial difference between spruce, fir and pine.

If you want to do anything outside of what's permitted by the book, that's generally when you call an engineer.

It does seem to me that a lot of calls for formalizing things in software is trying to skip over the engineering step and jump straight to a codebook that crystalizes the common engineered solutions into a list of dos and don'ts.