Most messed up unintended implications of world building you've encountered in a fantasy novel?

I've just been reading the first book in the "Skullduggery Pleasant" series. It's a fun little YA fantasy-detective novel, and other than your normal YA tropes being fairly front and center, it's a fun time. I've enjoyed it.

The basic premise of the world is more-or-less just ripped directly from Harry Potter: there are people who can do magic, and they operate in the shadows and hide their society from most "normal people". The main character, who lives in our world, becomes aware of this secret society, and begins exploring it and learning all the stuff about it.

But early on, as they're establishing the world of secret magic-users and how they operate, it's casually dropped that every community of magic-users on earth tries to discourage normal people from finding them out by disguising their neighborhoods as poor, run down, and crime ridden.

The mentor character then says (I'm approximating) "Any neighborhood that looks like this is gonna be secretly all magic users, and all these small run down houses are bigger on the inside- probably mansions."

So, while I'm sure the author didn't intend this, they just implied that income inequality doesn't exist in the Skullduggery Pleasant universe. Or at the very least, it exists on a much smaller scale. Every single poor neighborhood on earth apparently is just disguised to look scary to normal people, all of whom are at least middle class. Inside every run down, uncared for house, you'll actually find a secret magical mansion where magic-users are thriving!

I'm overall enjoying the book, but I can't help but cringe thinking about an underprivileged middle schooler picking this up, enjoying the escapism of the story, and then discovering a few chapters in that in this fictional universe their financial situation is a conspiracy created by magic-gated-communities. They can't even fantasize about being whisked away to the secret magic world, since their entire tax bracket is a lie.

So I got to thinking- what are some of the worst unintended implications of world building in fantasy stories? Harry Potter has quite a few, but I'm wondering what other people have encountered / can think of.