I entered "online dating" in Google, and I found some of the results are "local" (I'm in Ottawa, Canada). In the attached images see the results for www.okcupid.com and www.eharmony.com.
Is this something Google does automatically or is there some metadata that the sites publish?
This is something that Google does on its own. Their search results, by default, are personalized to each user. It is based on factors such as location and search history.
Sometimes when I am logged in to Google, it displays a different result vs when I am not logged in. I think it works by your location/GPS. Sometimes I get a different result on my phone.
Good observation!
Google observes your location and then gives more preferences to pages which are listing for online dating and which provide geographical information (in this case Ottawa, Canada).
Notice the URLs of okcupid.com and eharmony.com ... I visited those URLs, and the content is also quite unique (okcupid lists members in that area, and eharmony talks about Dating in Ottawa). Even the pof.com domain is an example of same (notice the rich snipper description talking about Ottawa Dating).
If you want to see the search results without the personalization (taking away your geographical location as a cue for personalizing your search results), then do this -
Toggle this switch here and you should see a different set of results.
Your search results depends on the location from where your are searching. Google search engine prefers to show local results primarily. The result shown in the is quite obvious as the content in the result pages is related to members of ottawa and dating information in Ottawa. So these results are relevant according to Google and hence have show at the first preference.
