Could you shed some more light on this? Instacart claims to offer in store prices for my local store.
Although I have caught a few issues where they charged double for an avocado or something like that but it seems like more of a data entry error based on the current price of "2 for 1"
Oh, they don't have that feature in my area (yet?) - if I browse Instacart for Trader Joe's, I see "15%+ higher than in-store pricing" and it is generally on the plus side more than the 15% side. (The average markup seems closer to 25%, it is a really really poor deal.)
IIRC Instacart also makes money from the price difference of products that are listed at their regular price yet are offered on sale at the store when actually bought by an Instacart shopper. That may have changed since their early days.
At least in my area (Chicago), Instacart is now offering in-store prices for some supermarkets.
DoorDash recently launched in my neighborhood, and I've noticed that prices are there are significantly higher, to the point of adding $5-10 on to the price of the same order from Grubhub