Several of them have dark stores in London. I think it probably makes some sense in large densely-packed cities, and if you go the whole-hog approach like Ocado then you can eliminate the picking staff. Even with manual picking though, it usually makes sense to use a different type of building in a different location rather than closing an existing store, because you don't need a car park, or a central location or trolleys, or high footfall. It's also pointless letting your valuable existing customers from that store stare forlornly through the window at the things they are no longer allowed to acquire
The fact that you can operate it out of an open store has a lot of benefits anyway. It minimises vehicle mileages, and it means you can still provide a valuable community service without additional cost.
Finally, a dark store still doesn't solve your problems. You'll still get breakage, or misplaced items, and you still won't know 7 days out when people are making the order whether the supplier is going to have issues.
Amazon appear to manage it because you typically order less than a tenth the number of items in each order, and all of them are ambient and have a long shelf life. Even then they are often fudging it by offering slightly longer delivery times, and if you order half a dozen things they usually arrive in at least 3 separate deliveries, often from different parts of the country. Dark or not, supermarkets are generally providing a better solution to a harder problem