traditional grocery stores won’t put in any effort to provide it
At least where I live here in Finland, traditional retail chains are very much in the shopping delivery business. Exactly including using their vast retail stores network as their base of deliveries. However again their stores are actual stores.
The dark stores would have had choices. For example don’t run a purely dark store. Run it as combined delivery base and retail store. The walk in retail might be minority of the business, but then they could say “no, we also have walk in customers. We aren’t a dark store, the city mayor is free to walk in and come buy a bottle of cola from us.”