They don't always respect this. I've had multiple Instacart shoppers replace items without marking them as replacements, including replacing some of them with things I explicitly indicated I did not want as replacements.
A company I do contract work for banned Instacart from one of their local stores entirely due to customer complaints to store management about unapproved substitutions.
I'm curious what metrics are driving that behavior by Instacart shoppers. In my (entirely amateur/armchair) opinion, it would seem like the time you'd save by making an unapproved substitution wouldn't make up for the potential for negative reviews, which could get you driven off the platform entirely.
Maybe a majority of customers don't care enough about unapproved substitutions to review poorly? Though reading through this thread suggests otherwise. Maybe there's some other internal metrics which shoppers or Instacart have access to that incentivize poor substitutions in the name of speed?
Honest questions - I don't know anything about this business and it's interesting to me that it appears to be such a pervasive issue.
Purely out of curiosity, how do the store police this? (I'm not very familiar with how Instacart operates, but I thought it was just a person going to the store as a normal shopper in your stead.)
I’m pretty sure the shoppers pay with a special card. They probably just tell the employees at the check out counter to refuse service to anyone with an Instacart branded credit card.
In Canada at least, the Real Canadian Superstore chain has set up InstaCart as their "official grocery delivery" partner. When you go to the Superstore website and click "Shop Delivery", you go through an InstaCart flow.
Although I suspect complaining to either the store itself or to InstaCart is going to be relatively futile, it seems that having the store managers bubble their complaints upward to regional managers may be more effective than complaining directly to InstaCart. Corporate makes decisions like that partnership, and if all of the store managers in a region are making the same complaint to HQ, maybe something might change. Maybe.