It is also likely that Holders maintain favour with their commoner subjects by allowing the services of slaves (house keeping, child care, mundane tasks such as shopping and logistics around the local town). So long as the well being of the slave and responsibility of ownership has a transferable element, and the beneficiaries of delegated slaves are god fearing citizens, it is possible that a 'household figure' could represent the dispersal of centrally owned slaves to the subjects of that authority.
Amarr society is far more complex than mere slave, serf, commoner, noble, holder tiers. The interplay between holders and their less socially powerful peers is likely a large driver in where slaves end up - so long as they are being raised in the name of god and Amarr of course.
This reasoning is purely focused on domestic slaves, not industrial, specialist or other subdivisions a post-space-flight society might require or desire.