Building codes aren't necessitated by having individual parts of lesser quality - if a part doesn't meet its required specifications then the overall assembly i

Building codes aren't necessitated by having individual parts of lesser quality - if a part doesn't meet its required specifications then the overall assembly is deficient regardless. Rather they're due to the tendency of builders to want to save money/labor by skimping on materials which only shows up long term (say putting studs 24" OC, or using 2x3's instead of 2x4's), or the adoption of cheaper less robust types of material that fail less gracefully (eg romex vs AC, drywall vs veneer plaster). Plus increasing risk adversity due to increasing wealth, and enough data to know how these systems actually fail in practice to make a meaningful difference. Building codes are basically part of and a response to our ever-increasing ability to analyze designs ahead of time - such analysis tells how we can make something less expensive while still meeting the requirements we're aware of, while codes make us more of ever more requirements that had previously been met by an overspec'd design.