They must be including the cost of the groceries in as revenue. However, there's a good question as to whether or not they are allowed to include this as reven

They must be including the cost of the groceries in as revenue. However, there's a good question as to whether or not they are allowed to include this as revenue or not, similar to Groupon. Revenue recognition is going to be a tricky one for them, since they are clearly distinguishing themselves as the delivery agent for stores like Whole Foods, Safeway, etc. This, and the question of whether or not their workers are actually contractors or employees are the two biggest issues that I would be curious about. If history has any bearing, I think Instacart, Uber, etc will face the same outcome that Microsoft did with their "contract" workers, ie. they will be deemed employees and will have to pay up.