Instacart and Shipt (who was recently acquired by Target) make money from the price slew between what they're paying (which, might not even be the cost that's on the grocery shelf -- it may be lower), and the price that they're charging you.

Yes, they have to pay the Shoppers a per-item fee, but, for the most part, the price that Insta is paying isn't the price that's listed on the shelf.