She has an authority to do so, regardless her wealth. I would say its her responsibility to protect people in her land and enforce the law.
In addition, I don’t think she has a lot of knight just for show, no? Yus can cut off nobleman’s head and she, the head, cannot cut down illegal business established by commoner within her land?
And if i understand correctly, they are not poor now. They are wealthy enough to be a target of nobles.
You are right that the illegal business must be backed by nobles, but I think if in is in her land then that noble must be her vassal. And even if she expose that illegal act, it should not be a problem for her since she have so much power as a duchess. I didn’t see that any ppl can easily kill her at this point.
Also, I don’t think she is afraid of dying by the hand of ppl other than Yus tho (if i remember correctly she said so herself that she now not afraid since Yus gave her a promise not to kill her)
I just really hate it when i see ppl who in need of help being ignored. Even if i love to see a beautiful castle, gorgeous dresses and grand party of these type of manhwa, the fact that they barely think about ppl under they rule make me feel bad. I just want to see MC show that they do care and being considerate toward their ppl.
Just a little is fine, just to show that they worth to be cheer for.
You're taking slavery waaaaayyyy too lightly. That wealth and strength she has isnt anything compared to the underground. Not even the king would be able to fight the underground without suffering severe consequences. I mean they even showed their standing with the underground. One of her vassals is literally connected to the underground. Slavery is much more complex than youre making it out to be.
Lets say you are a minister, there is someone telling you that there are human trafficking. You say “oh no i cannot help you with that”.
And when one of your family members got kidnapped, you go pay for your family. Then leave other slaves without a second thought.
That is how i see it.
I know this is a romance fiction, but idk, maybe i just need them to act like a hero since they are MC? Or i just kinda can relate it to my current situation in my country. lol

Why don’t FL just destroy and save ppl in slave market if she is really pity unfortunate ppl? I mean, its illegal and she have a power to save many ppl openly... I love the story so far but I’m kinda disappointed here, seeing how ignorant and narrow-minded FL is.