I think many are trying something along these lines. The devil is in the details.
The shotgun needs to be reloaded. The system needs to be reasonably reliable and durable. Feels like the range of the shotgun is also a problem. The system needs to have some sort of friend vs. foe identification, possibly not shoot at birds or other random objects. The camera needs to be able to deal with looking at the sun and low light, day and night, likely needs to be able to scan. Pretty soon you get to: https://en.wikipedia.org/wiki/Phalanx_CIWS
My point was once you start adapting to all the requirements you inevitably end up with a more complex system. Another thing that happens in a war is that the enemy will adapt to what you're doing.
The principles are fine (well, not sure camera is the right only sensor but aside). The actual engineering of a working system you can use in real life is complicated and that's what many are working on.
A Phalanx_CWIS is overkill. Also, I suspected that the system received continuous upgrades throughout the decades.
Likewise, the Abrams tanks are cold war era tanks, but they are continuously upgraded that a modern Abrams tank isn't really a 1980 tank. Modernization is likely to remove some weight and make Abrams more survivable against drones, in response to the Russo-Ukrainian war;
The shotgun needs to be reloaded. The system needs to be reasonably reliable and durable. Feels like the range of the shotgun is also a problem. The system needs to have some sort of friend vs. foe identification, possibly not shoot at birds or other random objects. The camera needs to be able to deal with looking at the sun and low light, day and night, likely needs to be able to scan. Pretty soon you get to: https://en.wikipedia.org/wiki/Phalanx_CIWS