Is there any neighborhood, anywhere, that with a small bit of research one can claim some sort? I mean Harlem is obvious, but Manhattan is full of yuppies (or Jews, I do not know NY). Queens I'm guessing is working class Italians and Irish (re: mob ties and drunks)
I don't know many cities neighborhoods, but don't they all have chinatowns, a gay neighborhood, a black neighborhood, 1 or 2 ethnic neighborhoods, a gated community are ("F! the 1%"), etc.(Yes, there is intermixing, but do you think Whitey Bulger in South Boston, or Italian mafia?)
Housing discrimination is a different beast, but you're sort of missing the point. There's a difference between self-segregation and discrimination. In theory, there should be nothing wrong with the former because it speaks to a human impulse to in-group biases. In-groups are not necessarily based on religion, national origin, or race but in practice in the United States they often are (as well as income level, education, etc.) due to historical circumstance.
Most people want to live near people who look, think, and act like them. It's natural. I'm not a believer in diversity for diversity's sake. The only problem is that, in the US, separate is inherently unequal because of historical practices like redlining and how cities developed, follow by divestment in poor communities - and people of color are, on average, much more likely to live in a neighborhood of concentrated poverty (and growing up in a poor neighborhood, even if you're middle class, actually impacts you more than growing up low-income regardless of race).
The issue with housing discrimination is that it actively prevents choice. People have the choice to create Chinatowns and Southies and often do because of in-group biases, and they should have the choice not to live in them, as well. But with redlining and other discriminatory practices which were outlawed in 1968 (but still happen in less obvious and systematic ways now), people were actively prevented from living where they wanted to and could afford to live. When a black person (or immigrant) moved into a neighborhood,
everybody's mortgage was downgraded and most people couldn't afford their homes. So they moved. Not out of hatred, but out of realistic self-interest. And then they created covenants where the neighborhood wouldn't sell to black people or immigrants - because they knew they would lose their homes, not because they hated black people.
(For this reason, I think it's not useful to conflate racism with bigotry. Bigotry is a corruption in the souls of people. Racism is a corruption in institutions and systems. People can benefit from racist policy out of self-interest without being even remotely bigoted themselves)
Refusing to rent to people from Manhattan specifically because they were from Manhattan would not be discriminatory because geographic discrimination is not actionable under the Fair Housing Act and because Manhattan is a diverse geography (refusing to rent to Jews from Manhattan would be actionable, obviously). On the other hand, there would be a strong case that refusing to rent to people from Borough Park, Brooklyn would be actionable because Borough Park is majority Hasidim.
This is, after all, why courts exist, to hear arguments and decide based on the law whether something is unlawful or not.
The relevance of housing discrimination to this case of selling tickets, though, is almost none. It would be impossible to make the case that "not living in Seattle" could constitute discrimination on any of the protected categories (race, religion, color, national origin). Instead, the argument would be that it is an arbitrary discrimination with no legitimate business purpose. But, as I've noted before, the argument that there
is a legitimate business purpose is much stronger.
