Everything.
Retail stores are logistics. And part of that is product flow. There are trucks coming in every single day. When you buy an item at a store, that item is deducted from the store's inventory, when that item's stock reaches a certain threshold, an order is immediately placed to the distribution center, and that item is loaded onto a truck and could arrive as soon as that night.
There's no reason to keep anything "in the back" except for high demand items that aren't brought in by a vendor and overflow from items that didn't quite fill a shelf.
I would have worded this slightly differently.
The store is the warehouse and the store owner is allowing self service inside the warehouse but not at checkout.
Having robots means you're automating something that your customers would have done for free. The automation is an additional expense and does not reduce your operating costs.
The online grocery business model only works for two types of customers: those who are willing to pay a premium for convenience and those who need some specialty products that local grocers don't sell.
The first market is a competitor to doordash, this either means automating the in-store pickup or the delivery itself.
The second market is actually a drag on your local grocery stores. You don't want to carry niche products that are only interesting to a tiny portion of your market e.g. products for rare food intolerances, groceries for expats. If you want to carry them in your store, you'd want the customer to preorder them themselves, so you know exactly how much you need and then make them pick them up.
Basically the correct business model is in-house doordash (or B2B doordash) combined with preorders.
Right, I just meant that you have a high chance of seeing the bread and drinks/chips getting delivered. They turn over pretty much daily. I would imagine it is the condiments and other very long shelf stable things that you may not see getting restocked on a daily basis?