How they cannot be compared? The metric here is the rate of death and the probability of incidents. The goal is to reduce suffering in the most impactful way as possible.
Be careful, applying your engineering mindset to real life. We cannot quantify the human experience. Let's take one tiny minutiae of both incidents with the strong and clear prior warning that there are countless examples of these points: in general, a parent would expect her child to be safer watching the Boston Marathon than standing several feet from a fertilizer plant. That's an expectation that, while your data might consider it irrational, is part of the human experience and why numbers cannot quantify what we feel.
You just can't apply numbers to being human. It doesn't work, it will never work, it's really disappointing to see people try, and I notice engineers try to do it more than most people I spend time with.
> That's an expectation that, while your data might consider it irrational, is part of the human experience and why numbers cannot quantify what we feel.
You seem to be claiming an axiom that we should make reality conform to our irrational emotions more than our attempts at rational analysis -- I think what you're hearing from other engineers is that they've experienced the same conflict and have decided that it's the emotion, rather than the rationality, that ought to leave when deciding how to act.
If you disagree, I think that all you can say is that your personal opinion is that life is aesthetically more pleasing when you stop attempting rationality. I think you should try to recognize that this is just an opinion you have, and not some objective truth that everyone else is failing to acknowledge.
But the child IS safer at the Boston Marathon, even considering what happened. How many people have attended this event over the years? Now how many have been maimed or killed in those years?
Parents also assume that their children are safer swimming in their backyard pools than standing several feet from a fertilizer plant, yet swimming pools are orders of magnitude more dangerous. I'm not sure what you're trying to say, exactly. Ignore the statistics because they don't account for the "human experience"? What is the goal here, preventing senseless deaths or preserving the "human experience"?
