We factor things we are used to into our daily lives. Someone slipped in the shower and died? That's just how things are. Someone eaten by a shark? That's big news!!! I think the best way t describe it is "familiarity breeds contempt". We're not scared by things we are used to.

I mean, conditioning. The first time you swim is fucking terrifying, but once you realize it's not that hard to not drown in still water, it's not that scary.

But this isn't really a universal law - hunger and food, for example. I get intensely hungry every day and feel the same intense relief. It never ends. I get the same intense anxiety in new social situations every single time, and I have to do that a lot at my job. I also used to be a heroin addict and I got the same intense sickness and the same intense high, as long as I could afford it, every day.

I think the real answer is just the concept of "normal."

Plane crashes are rare because when they do happen they're so horrible. Dozens or hundreds of people may die, and millions of dollars in damage could result. So to minimize plane crashes, we've set up a whole system of safely building and flying planes with tons of regulations and years of training for the few people that we let fly planes at all.

In a car crash, only a few people might die, and often just the driver...so we let pretty much everyone drive a car with minimal training. Therefore, quite predictably, there are more car crashes than plane crashes.

But if we wanted to, we could make car crashes just as rare as plane crashes! Getting a drivers license would be limited to a few thousand people, require thousands of hours of training to get, require frequent re-certification, and there'd be nearly no tolerance on having a license ever again after making even a small accident. We do all of the above for pilots, precisely because plane crashes are horrific when they do happen. But for cars that much control is unnecessary vs the smaller risk presented by car crashes.

So, at least for your example and other human-related things, it's kind of self-balancing: The worse a potential outcome is, the more time and money it's worth spending to make that event as rare as possible.

In the case of a plane crash, it's caused by human effort. A plane crash is much deadlier, so we regulate airplanes and pilots way more than we regulate cars and drivers and force it to be less common.

This isn't a universal law by any means, but most of the time it's true it will either be confirmation bias, normalcy bias, or a case of humans forcing it to be true because extremely common horrible things aren't good.

It's also caused by how you construct the question. Pairing plane crashes and car crashes together is completely arbitrary. I could pair watching a movie (a common experience that elicits a strong emotion) with watching the paint dry (something extremely boring that I never do). I could pair going on a run every day (which gets my heart and lungs pumping) with going on a plane ride (which is honestly pretty boring). But there's no real reason for me to do that, I'm just creating whatever picture I want.

In places where events are both frequent and deadly, humans (or life in general) can't survive. Life evolved on Earth because it happened to have the right conditions for it. The other planets in our solar system don't, and as far as we can tell, have no living organisms on them. On a planet that was regularly being hit by extinction-event level meteorites, complex life forms like humans would probably just never evolved.

From there, we have both evolved to be adapted to our environment and have used technology to further engineer solutions to major problems. If we couldn't survive getting wet, rain would be a frequent and deadly event. So we evolved to be able to survive being rained on. We built our cities in places that were relatively stable, not on top of active volcanoes. We use technology that is relatively safe (like airplanes) and avoid using technology that is unstable and dangerous.

There are plenty of examples of both natural events and technologies that (if they were widely used) that would qualify as "intense and frequent". We either avoid them on purpose, adapt to them, or are living on a planet where they don't happen because on planets where they do no life has evolved in the first place.

So, basic risk management is probability x consequence= risk. You determine what level of risk you are OK with and then manage your work to control that risk.

So, the plane example: The number of acceptable deaths of passengers in the airline industry is zero. Plane crashes kill people and harm business reputations, so the entire airline industry is designed to push the probability of an airplane crash as close to zero as possible. It's a catastrophic consequence. Everything is designed to keep planes in the air and there is a litany of back up systems to prevent crashes. Absent of a strong system of maintenance and checks, way more people would die as plane crashes would be more common.

Now, car crashes? The number of acceptable deaths on the road is apparently not zero based on our laws (sadly). Car crashes are kind of individual tragedies that are treated as effectively random. So, low consequence x medium probability < risk tolerance.

That's a bit of a macabre example, so let's use something more mundane. You run a factory. It produces widgets basic and widgets deluxe. The former sells for a $1. The latter sells for $1000. Which one is going to be more reliable?

If the $1000 widget shits the bed, it's a big deal. It costs a lot to fix it if there's a warranty and no one wants to buy an expensive widget that is unreliable.

So, you take steps to reduce that probability. You test and check more. You spend more on better components. That type of stuff. As a result, your intense consequence happens rarely.

On the other hand, a $1 widget? As long as the majority work , who cares? Your appetite for risk is higher so although you know that your units are defective at some higher rate that's just fine. The consequence isn't high enough to care about, so the frequency goes up.

In natural phenomena, it's different. You basically have to have force build up and release. So, if you have lots of small earthquakes that is going to reduce the overall odds for a big one. If you have frequent deluges from a lake, you probably won't have a catastrophic flood.

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