Cipher text can look a lot like randomness to the uninformed observer. If a deterministic system produces results, but the observer cannot model the underlying process from the results, are those results now random?
> "Bell's theorem rules out local hidden variables as a viable explanation of quantum mechanics (though it still leaves the door open for non-local hidden variables, such as De Broglie–Bohm theory, etc)"
Yeah, but there is an important subtlety. Quantum mechanics has a bunch of things that can be /modeled extremely well/ by random variables. But it might still turn out that that they are deterministic in some complicated way.
Then we would be back in a universe where we have an extremely useful concept in the humble random variable, and no examples of anything that is fundamentally random. If I start with a random variable, I couldn't reasonably approximate it with a real phenomenon, because the phenomenon would be deterministic.
Compare that to a line - I can define a line between the center of mass of my two hands. We can quibble all day about whether that is a well defined definition (I suppose it isn't), but if I wanted to approximate a real line with two points in space I could.
I contend this is an interesting an important difference between subjects like geometry and subjects like statistics. The underpinnings of statistic are _extremely_ philosophical.