Delivery shoppers wouldn't be able to pick out the good stuff if it's delivered by drone or whatever.

They could if there are human pickers.

In any event, delivery doesn't always mean the worst of the produce aisle, and while I noted that the incentive of tips might not transfer to robots, keeping repeat customers might be enough incentive for a way to be found to not make robots and grocery synonymous with only frozen food. That might mean human pickers; better automation on the food selection system; pre-inspected, washed and packaged fruits & veggies; etc.