Its like many things. A shot in the dark at taking the right steps.
But doesn't stop or prevent some companies from simply using the same inputs of the las house they did of that same sq ft a style.
No one looks at it close before issuing a permit. Maybe if there is a complaint later.
So, its probably more about money. Since the code enforcement department would have to send people to classes to learn how to do load calcs, and then have them recheck each one. Before they issued a permit.