Items sold in online grocery services are also marked up higher than they are in stores, for example: "Celeste Frozen Pizza is 99-cents at ShopRite, $1.29 at Peapod and a whopping $2.69 at FreshDirect"(source: http://6abc.com/archive/8983520/)
It also assumes that people can be home for the delivery, neighborhoods like this might not be the type where you want $50 to $100 worth of groceries sitting outside your apartment building.
Making the actual payment is another thing to consider. Not everyone has credit or debit cards. It looks like online grocery sellers also can't legally accept EBT, Wic or other food programs for online grocery delivery: https://www.facebook.com/notes/peapod-delivers/why-we-dont-a...
Online groceries require planning, time, and at least for the foreseeable future will come at a premium cost. It's great for certain people but I hope it does not become the only option for groceries.
Of course they could, but those who live in food deserts aren't those who would (at this time, at least).
I understand Co-Op's offer more cheaply priced groceries and that's a great community project so I'm not suggesting Co-Op's have no point. They're great things. I'm just wondering what the difference between big box grocery stores and online grocery delivery is?