Yes, I agree. If you're writing a list for yourself, a bare "coconut" is a typical entry. But if you're dictating a shopping list to someone else, you're quite unlikely to say "coconut" because that isn't grammatical.

So it turns into a question of how people think about dictating to Alexa.

This is a good point - in reality Alexa doesn't really have to do a great job transcribing at all if it's just constructing a list as a reminder for you later.

If this is a precursor to being able to quickly voice order stuff off amazon to be delivered though it's a different story.