SFO has a very Vietnamese-themed offerings - spring rolls and similar items (it's not just Asian but specially Vietnamese) LAX is very Americanized offering with no clear theme. NRT offers a little from different cultures, like sushi with those cute little squeeze bottle soy sauce but then French deserts. I like NRT a lot but I think the flavors clash with each other.

I think Delta is trying to add a local theme to the offering which is really nice.

Whatever they do, just leave a big bucket of Biscoff cookies - it's the only reason I fly Delta :P