Satellites can't take air samples to check for radiation, for one. Nor do they deliver a hellfire missile to a target.
Satellites in low orbit pass overhead rather rapidly. Drones loiter, and grab excellent photos, even in, shall we say, non-visible spectra. Satellites in high orbit may be stationary over a target, true, but the extra distance in that high orbit negates much of that optical resolution. Better to have a low-flying drone.
Sauron
Better to have a low-flying drone may be true but is the risk worth it?.Can they use the tech to find a way to down one?.