>Aircraft need to be able to see other aircraft so as not to collide with them. Especially so if you foresee a future where delivery drones are as common as cars.

Cameras are not being used for this job.

>They also need to avoid obstacles that aren't on their digital maps, like newly erected cranes, and moving things like birds, parachutists and gliders.

Cameras can be used for these, however it's better to use other sensors as the primary means of detection.

I'm guessing the camera isn't used for aircraft separation since nearly everything has ADS/B now.

ADS-B out is only required for manned aircraft flying in and out of controlled airspace.

There are some other exceptions as well IIRC for gliders, ultra lights and some others.