Nailed it.
There are still huge areas of our planet that have very poor sat imagery. Sadly, some of the most interesting and rugged regions are neglected. I can only guess that if no one lives there, no one cares. The region I spend most of my life has a population density of around 0.0062/km2 (0.016/sq mi). Not much data, but I know of more than 50 airstrips among the mountains, along the rivers and streams and tucked beside azure blue lakes.