It worked in China, clearly, so why not in the US ?
Joke aside, fixing people joking about each other is a lost battle. Listen to them speak about diversity behind closed door (I'm a minority in the country I work in, I hate these things so much making me feel different when I try to integration and assimilate), it won't be utopian paradise-style speech either.
Let the warehouse worker mock the headquarter, let the headquarter mock the warehouse, it's not the problem and will happen within the border of whichever gradient. Parisians mock Normandy, Europeans mock Americans, Aliens mock the Earth, your friend's office mock the field workers...