This is true and most of what is exempt is work that is of a cosmetic nature only. However, this must be considered in light of how and why building codes have evolved over time. (Actually, a very long time; the earliest building codes can be traced back to the Code of Hammurabi, circa 1760 B.C.) The enactment of, and revisions to building codes are generally a direct result of failures from existing building techniques, and the disasters that often were a result of those failures.
Although the complexity of the codes have increased since the days of Hammurabi, what was true then remains true today; the intent of the building codes is to protect lives in the buildings and facilities we occupy and use.