Could someone please explain to me why is it "på restaurant" in this sentence but "i restauranten" in "servitørene jobber i restauranten"?
Both prepositions are acceptable in this context, with "på" being somewhat more common.
wait, isn't "restauranten" the restaurant, whereas (I don't know why there isn't an indefinite article in front of it here??) "en restaurant" is "a restaurant"
I think they are interchangeable in this sentence
what causes us to drop the indefinite article before restaurant in this case?
It's because the focus isn't on any specific restaurant, but on the act of working at one. You can treat it more like a verb phrase, akin to "å gå på kino" and "å kjøre bil".
I hear restauranten, but was marked wrong.
The voice is clearly saying 'restaurant' here, so it should be fine :)
Is servitør used for both, waiter and waitress?
Yes, you can use "servitør" for either gender.
"Servitrise" is the strictly female version, but there's been a shift toward gender neutral occupational titles in the past few decades.