Toothless, since it's impossible to prove that any given message is or is not encrypted.

This comment I'm writing right here might not mean what it appears to mean, and might not be aimed at who it appears to be aimed at.

It's effectively merely illegal to pollute the shared medium with noise.

I can imagine somebody could make with some AI a system that talks something that makes more or less sense, but has encoded information in the message

I didn’t mention CB, any particular frequency, or country. My comment was on secure communication at the abstract / theoretical level.

In principle, yes. Technically, no. D-STAR vocoder.