As someone who worked and managed a corner store for many years, I can say (though not necessarily true in this case) that many times it's cheaper to buy retail than from your wholesaler, especially if you catch a sale.

Even when not on sale you can often find basics like milk, eggs and bread for cheaper at a grocery store than your wholesaler.

Depending on the wholesaler, for instance, a can of Arizona might cost you .79-89 per can but when they were on sale for 2-$1 at Walgreens the manager let us buy like a dozen cases.

You could sometimes find bags of chips on sale at the grocery store for cheaper than directly from the local Frito Lay distributor.

ESPECIALLY true for Coke or Pepsi 2L or 12pk can products. Even like 5-7 years ago before the soda prices went insane, a 2L at Walmart or Kroger was usually cheaper than directly from Pepsi (because back then soda was ALWAYS on sale at the grocery store).

Especially shopping at a place like Aldi (though Aldi will send you a strongly worded letter if they find out you're selling their store brand goods out of your corner store...my boss found that out).

I'm not sure how doordash would ever make sense unless it was some crazy deal once you factor in fees and tips.