There's a pizza place up in the Tenderloin (SF) that I occasionally order from (I used to live a couple blocks from them and would walk in all the time). I would order on Grubhub because that was how they were set up to do delivery. (I believe they link to Slice from their website now for delivery.) The delivery person was always someone from the shop itself, not someone who worked for Grubhub. Now I wonder how much GH was skimming off the top, even though they weren't really providing all that much.