What are commercial operators doing? Another limitation of Amateur bands is that they can't be used for commercial purposes, so licensed commercial drone operators must be using commercial bands where cryptography is permitted. Don't know myself; haven't looked into it.
I don't think so. I think we can agree that many, many commercial operators use DJI. There are also lots of amateurs using DJI. Both use the same firmware. There is no option for me to encrypt or unencrypt my Phantom which I could easily use commercially if I had my FAA Part 107.
[1] https://www.govregs.com/regulations/title47_chapterI_part97_...
Would traffic that is not encrypted but is instead authenticated (with a MAC tag or AEAD'd) be allowed? What are the exact FCC rules and laws at work?
While systems can encrypt MAVLink messages in transit, I have not seen it actually done- everyone is relying on security of the physical layer (i.e. obscurity of telemetry radio frequency hopping/channel negotiation, WiFi security).
So in most implementations, MAVLink messages are actually transmitted in plaintext, over plain TCP/UDP connections.