"I can't think of an airline passenger who would be totally fine with the flight computer usually being pretty good."
Actually, I would think it's pretty much the opposite. That is, the only type of airline passenger I can think of, is one who is fine with the flight computer (and the airplane in general) usually being pretty reliable. We already know that computers can malfunction and airplanes can crash. Now, of course, how reliable you want the airplane to be is up to you, but if you want it to be flawless, then you should never board an airplane.
It's not just the examples that are flawed. In most practical situations, provably correct answers do not exist. In most cases, one can only choose a level of certainty. Sometimes not even the level of certainty is possible to know.