Re: What usage ?
Yeah, satellites are notoriously not real-time though, are they. Russia are reportedly using Chinese spy satellites, but satellites are typically in high orbits. (And Ukraine are being allowed to use images from European satellites).
With a satellite, if you want to have real-time surveillance, your options are pretty limited. Either you need to be in a geostationary orbit above your target, which means being in a high equatorial orbit, or you need to use fuel to remain above the target, which is both limited and expensive.
In reality, a satellite in an unpowered orbit (i.e. not pissing away valuable fuel that you have expended many times more fuel raising into orbit) passes over a target in a sun-synchronous orbit once a day. This also means that the pictures it takes are always taken at the same time of day, directly from above, with shadows at the same angle. This is clearly less useful than taking real-time pictures from a drone passing over a target, especially if you are trying to work out movements of troops and vehicles, which are almost certainly under cover a lot of the time. Spy satellites, on the other hand, are much more useful for pinpointing static targets, such as massive ammunition dumps, so that they can be made to make a loud noise and deprive your dear leader of three months' worth of ammunition.