Don,
Historically most builders did not have to deal with modern codes, and when the frame is buried in the walls you gain the shear by all that other stuff going on around the frame. I've moved 2 German style barns in Eastern PA that were very stout, and later a huge barn in MD that was surprisingly underbuilt. In both cases code really wasn't around when they went up, and even when they were moved the one that became a house (despite how stout it was) needed the shell for the engineers to sign off on it. The large MD barn went back as a barn... with little review required.
Just the nature of the craft. Some places require some pretty strict standards, others do not. It can be tricky depending on locale, code, size, and loading to get what many view as a traditional wood to wood joined frame to pass mystery without taking into account the balance of the structure.
