Why isn’t it a requirement that all ducts be smoke tested and repaired by the building code?

Good question. Even the AC contractors think that it is a good test because they are called back for complaints, in the summer, to climb into a 135 degree, unlit attic. Building Officials also realize that this is a superior test compared to plain visual inspection. There are many efficiency programs created by numerous entities with their own fiefdom to protect. Some are “energy efficient” in name only with little interest in proactively addressing problems.