Parts of the Pacific are littered with uninhabited atolls. Even a few decades ago, it was plausible to find yourself on one unlikely to be visited for many years.
An issue with satellite imagery is that it is focused on areas where people want to take pictures. Vast regions of the Pacific rarely if ever have satellite photographs taken at sufficient resolution to see anything a castaway does for the simple reason that nothing is there that would incentivize anyone to expend the cost of taking a picture. I used to have a global model of satellite imagery coverage based on actual imagery catalogs and much of the Pacific was barren.
An issue with satellite imagery is that it is focused on areas where people want to take pictures. Vast regions of the Pacific rarely if ever have satellite photographs taken at sufficient resolution to see anything a castaway does for the simple reason that nothing is there that would incentivize anyone to expend the cost of taking a picture. I used to have a global model of satellite imagery coverage based on actual imagery catalogs and much of the Pacific was barren.