I don't know the real legal reasoning, but in general the score for a symphony is quite a bit more detailed than the words on your grandmother's recipe card. IIRC, a piece of music 8 seconds or less cannot be under copyright (can't find any reference; sorry about that). I would think the typical recipe card would fall under that line of reasoning, whereas a page or two article on how a chef makes a complicated dish would probably be a creative work.
Length is a red herring; compare the copyrightable poetry in 'Haiku in English' (e.g., "tundra", in full) with signature dishes, like sachertorte or Waldorf Salad.
