I can't understand

I can't seem to understand why other people doesn't think of the red haired girl as annoying or like why it seems so easy for them to forgive her. Like, if I was shirone and a noble girl say that she'll sell me as a slave even if she meant it like a joke? I would hate her for that. Like duh? Obviously people who she payed for doesn't think of it as a joke. And that's really not a good joke. People should remember how being a slave isn't a joke even if it's just a manhwa or any fiction stories.