help get them back to their country??? get them out of slavery? Not use them as a child work force that you disguises as uwu wholesome because you gave them some soup and bread? or do i need to just pretend that its totally cool that the hero is just giving a metric shit tonne of money to feed into this slave system thats going to snatch and traffick more children so that mr. slave seller can sell the those displaced kids to the fucking insane perverts that we know are prevalent throughout the kingdom?
no matter how you approach the system, a legal market of slavery is fucking insane to have to interact with as a plot point or to even use as a gag, three seperate families decided to gamble their daughters lifes based on the fact that they know that sheild apperently loves slaves, not knowing if their children would get bought by their cult figure or again, if some creep with enough cash waltzed in.
"oh but shield hero told the slaver to send them home" why would we ever fucking trust this guy? he sells and trafficks children, he has no legal obligation to do shit except take in all the money the mc decides to dole out for the next batch of child slaves the manga wants to pretend hes saveing.
the slave stuff could have just been raph and filo and it would have been fine, a low point in the heros life that turned into a good thing, the orphans could have been from demi human settlements ABOUT to be sold into slavery and it would have worked JUST as well.
the slave stuff is fucking creepy.
On the girls family risking them, this was a deal they made with the trader. It's similar to the arguments about legalizing prostitution or drugs. Since this is a legally acknowledge trade, law enforcement can still be applied which also means that if the trader just abducts the girls or doesn't follow through with the contract, the families can send the police after him.
As for what Naofumi's doing with them, this is the follow-up to his arguments against the spear at the beginning. Also, though the author probably wasn't thinking about it, also serves as a criticism of the US's abolishment of chattel slavery while keeping penal slavery. That is, freeing someone requires more than simply saying they are on a document. The whole process at the village is that they, as mostly the displaced former residents of the territory, receive basic combat training and then get to choose their future profession where they get education/training for it.
To be honest about the US's abolishment of chattel slavery, it wasn't intended to be as half-assed as it was. Even at the time, they knew there needed to be support to KEEP them free afterwards. It's just that there used to be this idea that you should mix the president and vice president of different parties and, given the civil war, multiple parties joined into the National Union party. Though they both wanted to maintain the union, Lincoln and his vice president were from opposing parties and when Lincoln was assassinated, he had little interest in following through with his promises to the former slaves. That's why the slave owners got reparations but not the slaves.
Anyway, the point of this territory building sort of part where he's gathering all these slaves is about how he's starting to think about what happens to Raphtalia and the others after he's gone, the fighting is over, and everyone is free. You said it could have just been a low point, but it would be pointless to leave it as just a low point and not say anything. This isn't like how it usually goes in isekai were it's just a way of giving a weak-willed and timid teen an assortment of women who can't refuse that matches a variety of types for maximum coverage of reader appeal. Instead, it deals a bit with what has to be done so that someone can pick themselves after being enslaved. Could it be better, yes, it could do without the game system reasons to keep the slave marks on when they have no story relevance outside of that and the notion that it labels them as belonging to the Archduke of Melomark to potential attackers. However, there IS a way to approach it that is worth saying.
