>>A van can hold thousands of 2-ounce packages, whereas a drone can hold one.

In a perfect world, yes. In reality, no. You would need a perfect storm of a huge wave of orders all to the same restaurant (or cluster of restaurants) to be delivered to the same neighborhood to ensure timely delivery so the food was hot and the customers were happy. In real life, you are almost guaranteed to never hit the ideal conditions.

Edit: After re-reading your comment, I’d agree with you for the non-food deliveries. My comment was obviously focused more on the UberEats use case.