The law is in the Michigan Bureau of Construction Codes, but the inspectors can require anything above that. Sure you can tell them no and point at the code book, but do you really want to do that? Most builders know what the inspectors in the area want, and it's easier to just comply with them then have them make your life miserable. In Michigan homeowners are also able to perform their own electrical, plumbing and building as long as it passes inspection. I remember one electrical inspector that hated to inspect homeowners work and would discourage it whenever possible and make the homeowners life miserable. For one renovation, he told the homeowner he didn't want the green ground screws on the receptacles, he wanted them replaced with gold. The guy went to an electrical supply place, told them what he wanted, the guy behind the counter looked baffled and told him yeah, they can order them, but you need to get 5000 of them, why do you want them? The homeowner told the counter guy why, the guy went to the back office and made a phone call, came back and told the homeowner that it's ok to use the green screws, he talked to the inspector. It's unfortunate that the inspectors can do that. You would think the code books are there for a reason, not just as guidance, but in Michigan, that's how it is.