Location density of the deliveries has got to have a massive impact on their effectiveness. I'm highly skeptical of their ability gather groceries and deliver to 5 separate locations within 1 hour. Even in a dense area where it's 5 minutes between each location (plus parking, plus entry / exit and delivery) that's 25 minutes minimum.

The longer the time, the lower the $/Hr. The further away the locations are, the higher the transportation costs are for the driver, further cutting into their actual take home pay (not including, miles, depreciation, insurance, etc...).

Instead of making deliveries after the order (and trying to bundle orders and deliveries), I would think a dispatch model where one set of workers go out in the morning and make the orders and deliver to a central location. Then have a second shift make deliveries, but that would make it difficult to maintain the independent contract status of their workers.