I'd suggest that non-lethal intimidation wouldn't necessarily work on crows. Crows routinely mob other threat birds (e.g. buzzards, in my experience) and even a single crow will chase a buzzard off.

Firing bullets or similar from a drone might not be a good idea in a crowded urban environment (damage to people and / or property).

Drones deploying nets to catch them (or at least make them fall out of the sky)? Perhaps, until the crows cotton on, to the extent of swarming the drones.

Self-detonating proximity drones? Have the same issues as firing bullets (falling debris) and not very economic.