User blog comment:SomeoneYouUsedToKnow/SYUTK's V4E5 - Polystralia - Impressions/Recap/@comment-28288412-20161205152605/@comment-25936766-20161205160937

From the WOR:

"A village in Sanus fell under attack, and the only reason anyone survived, was because the humans and Faunus united against their common enemy. It was a step in the right direction, but it didn’t fix everything.

''Once humanity learned they weren’t so different from the Faunus, they still used those differences as an excuse to exploit and alienate them. The treatment of the Faunus differed around the world, and things wouldn’t improve much for them until the Great War: Vale and Vacuo against Mantle and Mistral. A war unlike anyone had ever seen, and when it was over, the world was desperate to find compromises that would ensure they’d never see the likes of it again.''

''Faunus were awarded equal rights as citizens of Remnant, and as an apology, they were given an entire continent of their own to do with as they pleased. There were some that saw this as fair and just, but many saw it for what it really was: a slap in the face from a nation of sore losers. And so Menagerie was born."''

---

In other words, it was given, at least officially, as a gift of gratitude, equality, and other related stuff like apology.

Faunus already lived in the kingdoms, they were just discriminated. Even if there was official equality, even if the war had just ended, they would still be (and were) discriminated. Remember black people kept suffering even decades after WW2. And still do in some places.

And in regards to working practices we've only heard of the SDC, from a very biased source, and we don't know if the SDC started said practices before or after they became the WF's favorite target.

By giving them a whole continent for them to do as they want, they don't have to live under hate and oppresion. They are free to do what they want. Mutual hate would remain for a long time, and why live under mutual hate and discrimination?