Doing home grocery delivery by hiring people to shop at the grocery store for you is like doing e-commerce by hiring people to go to the mall for you. Grocery stores are deliberately designed in the exact opposite way that fulfillment centers are; even “warehouse stores” like Costco are adapted to exploit consumer psychology rather than optimize picking throughput.

I have never had substitution problems with Amazon Fresh because “substitute one ASIN for another” is an absurd use case if you can reliably track your inventory and allow people to choose products based on availability. I’ve also been pleased with meat and produce quality; maybe I’m lucky, or maybe grocers have been getting away with stocking shoddy produce for years on the expectation that the customer can do the QC work for them.