I mean this theoretically works until the gangs decide to start putting small bombs in the drones that detonate on impact. I bet they can build drones faster than people can breed and train the birds.

"Lasers." (although, line of sight, point-to-point communication is admittedly less trivial to interfere with)

The point being that, if "criminal gangs" are up to no good, but they're parting their equipment with off-the-shelf Best Buy and Radio Shack products, they probably aren't programming DSP interfaces, aren't encoding and decoding raw bit streams, aren't masking binary objects with base64 blobs, aren't rolling their own encryption.

Or, if they are rolling their own encryption, they're using Excel spreadsheets to do it. [0]

[0] https://www.theregister.co.uk/2011/03/22/ba_jihadist_trial_s...

Does this work?

I had the impression, you can't out-light shadows for example.

There's a pretty bright light on between sunrise and sunset, doesn't affect free air optical transmission at all unless the sun happens to align with the sender or the receiver.

The biggest limitations are water vapor in the air, precipitation and dust. Also, the distance is rather limited compared to radio.

This doesn't work if the receiver on the drone is directed backwards and you usually are in front of the drone as its target.