Why is there a difference between Google sitelinks in .com search results and local results?

Question

I get sitelinks for a Dutch website in the Dutch search results, where I don't see them for the international (.com) results. Why?

See difference between:

www.google.nl/search?q=delta+birding

and:

www.google.com/search?q=delta+birding

UPDATE:

I figured out it has something to do with language settings (language in URL, maybe language of browser?):

See:

www.google.com/search?q=delta+birding&hl=nl

and

www.google.com/search?q=delta+birding&hl=en

Answer 1

Because they are two different sets of search results. In local search your site meets the criteria to receive sitelinks as Google considers it to be an authoritative source (you come #1 for me). But in international search you are not (you come #3 for me).