That is exactly my point. They are not going to be required for one- and two-dwellings only, but are required for an apartment or condo dwelling. A smart law firm representing homeowners can make the claim the state failed to protect their clients in the same manner that has been provided to those that live in other dwelling types. There doesn't even need to be a single injury or loss in property for a class-action suit of this nature to be filled. I worked for a rapidly growing city of 10-years. I can't begin to tell you the number of lawsuits that were filed against the City, state, and feds by a group of interested individuals that believed the law didn't apply or protect them equally with others in their community. The builder and contractors are typically named in the lawsuits. A huge amount of time and expense is incurred by those that simply followed the code.
And it doesn't have to be class-action. Let's say a contractor wires a single-family dwelling and an apartment dwelling sometime later this year. He installs AFCIs for the apartment because they are required by code but does not install them in the single-family dwelling because the code doesn't require them. Now lets say an electrical fire occurs within the dwelling two-years from now. Again, a smart law firm will question why AFCI protection wasn't installed? It won't matter that the state doesn't require them, what matters is that the contractor chose not to install them when he knew and installed this type of protection as required for other dwelling types. People that follow the letter of the law are sued all the time and found negligent and responsible for the losses imposed onto a victim.
If they don't work, then why are they required in other dwelling types? What substantiation was used to remove them from a one- and two-family dwelling? I hope it wasn't just cost. Judges and juries just love hearing that. You mean the death of this person or the $250,000 loss happened because you didn't want to incur the extra $300 to install AFCI devices? By the way, the feds consider a life to be worth about $9 million dollars in terms of lawsuits. Yikes...
This type of thing can also happen in states that are behind a code cycle or two. The local AHJ may not be able to require you to comply with the most recent published code, but that won't stop a lawyer from arguing that you should have done so to protect their client, simply because you knew about it.