Regular drones are awesome to make short missions (you need to check one electrical pylone or a small bridge - take a drone). But on bigger scale they don't have enough range to do this kind of operations. Also, they don't have enough payload. You can only fly with one camera, when the utilities need HQ camera, infrared, LiDAR etc. That's why they need to keep using helicopters.
Sorta like how railroads figured out it was much simpler operationally to have fewer types of locomotives, and use multiples on larger trains, rather than create dinosaurs like the DDA40x (https://en.wikipedia.org/wiki/EMD_DDA40X) that were ONLY useful in narrow circumstances.
Regular drones can't be used to inspect that much (too many drones required, too many pilots, too much aerial and ground risk - when regular drone fall they are lethal).
Airships won’t scale like that. You don’t have the benefit of tons of media companies buying airships to use as camera platforms.