Also familiar with codes, I would add the following, the code could require a separate water service with post indicator valve, un-metered or with full flow meter (big expense). The Service might add 50% to the nominal cost you describe.
Additionally residential is full of unheated spaces that are still combustable. You might add a big cost to use fire treated lumber (plus the chemical exposure long term) to have an unheated attic and still not have sprinkler heads there. Additionally the attic could no longer be used for storage due to code issues.
The ramifications are very extensive and would need to be understood by the consumer. I will agree, that it is not a valueless additional feature to a single family dwelling and also agree that other than kids with clothes hangers, accidental discharge is unlikely.
You are referring to sprinklers on a commercial installation. Home sprinklers are generally supplied by the domestic service and do not require a lot of the fluff that a commercial system does. Home sprinklers are intended for only "Life Safety" whereas the commercial are more in depth. Generally in a home fire system, attics are not required to be protected and fire treated lumber is not required.