I believe there is room for more innovation in groceries, but I don't think it's around automating cashiers and checkout. For one, people generally, and those who shop at Whole Foods specifically, like interacting with staff. Amazon isn't dumb enough to not know this. I assume they're also not dumb enough to not realize that happy, helpful staff aren't created via treating your workforce like robots.

I think that the biggest room for innovation in groceries is in just-in-time supply chain management. Obviously, the tremendous waste associated with having to stock a bunch of perishable shit at high quantities is a factor in keeping prices high. If Amazon can successfully use their supply chain magic to reduce inventories while maintaining adequate SKUs, then they should be able to keep wages decent, keep customers satisfied, and reduce prices.

I don't know enough about the secret sauce of supply chains to know if this strategy is viable in the grocery space, but if anyone can figure out predictive grocery shopping behavior it is them and their unfathomable computing power.