I really depend on grocery delivery services, as I live in an area without a convenient grocery store. I use Peapod (not same-day, and for some reason, has very little fresh meat or seafood), Amazon Prime Now (shops at only one grocery store in my city, and the software is very inflexible), and Instacart. I use Instacart the most, even though, in many ways, it's the worst of the three services. I like that I have my pick of six or so stores, but the accuracy of the shoppers is VERY poor. One problem is that, unlike Peapod, they have a poor catalog system (plus, the catalogs of the stores that you can choose from vary in completeness and accuracy). If you click on "baby back ribs," as I did recently, with a photo of a slab of ribs, you may or may not get what is pictured (one time, I got a small slab of plastic-packed ribs, another time I got short ribs of beef!). In the case of Peapod, what you see is what you get. I'm sure the software is correlated to a bar code, which then appears on the item on the shelf. With Instacart, the photo bears no relation to anything (I just saw a listing for ground beef that had a photo of a jug of orange juice!), so interpreting the request for an item is up to the shoppers, who are no doubt very rushed, and often don't know anything about food (one young man didn't know there was a difference between an"eating" and a "juice" orange).
The good thing is that customer service is very responsive, and when the shopper messes up, they'll rush a replacement within an hour, and give even you a credit off your next delivery (though you usually have to ask for that).