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.