Never, because it's impossible to have a platform if keeping something content up gets them fined AND taking content down gets them fined.
They don't have perfect knowledge of how a court would rule in each case, so they err on the side of caution. Remove the side of caution and you can't have a platform.
1) It's not that much money.
2) The skills are useful, unlike those in your flawed analogy.
3) Companies actually look at such things when recruiting contractors, etc.
4) You're an *.
You did. Right here: "e.g. ethnicity". That's a quote from you. I mentioned in-group, you added ethnicity.
> There you go. And yet history proves you wrong, starting with the roman empire and the middle ages.
At this point I wonder if you are trolling. The roman empire waged war on pretty much every single other ethnic group around them and enslaved them. Which the other ethnic groups around them were also trying to do at the time. Then we have the middle ages with the crusades and such... etc etc etc
Actually that's not what I said it all. The concept on in/out-group can be completely arbitrary, e.g. assigned by flipping a coin. The principle still holds.
That said, since you bring it up, the history of humanity is largely the history of war between different ethnic groups. So yes, hating people based on ethnicity has been the norm for most of human history. It's still largely the case in varying degrees in different parts of the world.
Well the history of humanity is the inspiration for Game of Thrones. People conspire to grab power all the time. That has been the norm and not the exception. The means change but that's about it.
They don't have perfect knowledge of how a court would rule in each case, so they err on the side of caution. Remove the side of caution and you can't have a platform.