This actually happened to some restaurants who found their service on DoorDash. The restaurant owners were able to make a fine profit out of DoorDash’s arbitrage scheme.

Don’t worry. If Amazon decided to undercut by selling at a loss, they would absolutely put it in their ToS that retailers cannot exploit this loophole and they would sue to enforce their ToS.

It looks like a good idea, this works better for refrigerators than pizza.