Forcing young orphaned adults into slavery would be considerably less profitable than doing so with children would be. Without the state paying for the means of subsistence for the adult slaves, that cost would have to be deducted from that roughtly 104k per head that Bailey extracts from the orphans themselves by force. On top of that, the costs associated with maintaining an adult slave workforce is significantly greater than the cost of utilizing child labor, which means that ultimately adult slaves would realize a fraction of the profit that a proper orphan child would, assuming that each generates a similar amount of income.
Adult slaves , at the rates we are talking about, would still likely be profitable enough to keep, but there would be quite a lot of extra expenses that would further eat into Bailey's rate of profit. There is no state system in place to keep adult slaves in bondage beyond the town, which means that escapes would be common, and each escapee would bring trouble that is expensive to deal with back to the town either in the form of a criminal element or in the form of legal hassle. Bailey would need to personally maintain the system that keeps the adult slaves in bondage. The problem with adult slaves has always been that they don't just go away when they are no longer being productive the way that waged laborers do. Keeping them in significant numbers the way that Bailey does thus becomes far more trouble than it is worth. Sure, Bailey could keep an orphanage full of adult slaves, but why? Keeping orphan children has a wildly higher rate of profit and is much safer and more sustainable.
