Just for the record, I haven't done Instacart, and my most recent experience with DD was a little over two years ago so I'm unsure if it's still done in the same way.
When I did DD it would pull up a map in the app to show me hotspots that were getting high volume of orders in the town/city I was in. I drove to those hot spots, and parked in one of the parking lots in the area until I received an order. It would give me a pop-up when an order was available for me that only said the location to pick the order up, distance I would drive, the pay for that order and ask if I wanted to accept it. Nobody was able to request me as a Dasher, the app would just ask me if I wanted an order. If I said no it went to the next Dasher to ask if they wanted it. I'm assuming that Instacart is the same way. I believe Instacart is done in a similar way but with groceries instead of food.
I think I've read about two occasions that the government handed money to ISPs to get Internet out to rural areas, and both times the results were essentially "ISPs pocket the money, nothing changes." It's infuriating, and I wouldn't be surprised if it's happened more than twice.