Um, I get that...but the original poster just said "2000 miles", didn't reference a travel class, and then said the agent told them kids meals were only available internationally, which makes me think they are seated in Y.
OP stated it was a domestic flight (EWR-SEA).
As far as I am aware, you can only pre-order (when operational) snack boxes and other snacks in economy; bistro items (e.g. burger) must be purchased on board.