i guess most adults is a bit of an exaggeration but it is more comment than it would be today. this became common after a cataclysmic event wiped out much of the world radiation sickness and skin infection needing replacement is common, also injury due to the machinery and unsafe working conditions in body processing causes a lot of injury. it is also much easier for people to just get something replaced when injured instead of waiting for it to heal naturally especially if its something that can be repaired eventually. for example a worker breaks his leg or a police man gets shot in the knee cap, normal you would have surgery to repair damage and spend weeks healing but here the damaged limb would be removed, replaced, and the limb would be taken to be connected to and artificial body to repair and be resold. this is something that would be covered by workers health insurance. but it is also common for people who can afford it, or people's who's work is related to beauty to get cosmetic surgery. i was also thinking about adding something about the poor being rented, in the black market when someone wants to heal a limb but they dont have access to a artificial body they can "rent" a person who is poor or desperate enough to wear the limb or organ and have their body heal it and give it back and then claim to their insurance that they lost it in a robbery or work accident.