Hypothetical scenario:
You ask a Global Entry passenger, "do you have food?"
They say "no."
You then find a granola bar in their bag.
Do you take any action? I use a granola bar in this example because it is food, but not meat/fruit/vegetables which are explicitly spelled out on the declaration form.
Follow-up to make this question more interesting: What if it's not a granola bar, but a pack of chewing gum?