Carmageddon is a respawnable, resetable, impermanent world.

Its a toy.

Fallout 1 and 2 are not, or at least not as much or not as easily... they are deterministic, event driven, complex, and permanent.

Its a story.

You don't tend to care too much about if some random team mate of yours dies in a team based shooter like Battlefield or COD.

Generally, they're all randos you'll never see again, despite being actual human beings on the other end of a screen.

You tend to care a lot if its one of your soldiers in XCOM or Xenonauts or one of your crew from ShadowRun Returns or Fire Emblem.

They're literally fictional characters, sometimes barely even actually characterized, but, you have history with them, shared struggles.

Your brain tends to care more about things that are harder to replace, decisions with irreversible results.... morality kicks in when we realize permanence is at play, that consequences actually exist.

... thats a long way of saying I do not know if there is a specific psychological term for all this, lol.

EDIT: Loss Aversion?

It might be something to do with the emotional attachment. We humans will bond with and empathise with basically anything, and we get rewarded with happy brain chemicals when we cooperate and build trust, so we tend to try and do it when the option arises.

In carmageddon they dont register to us as real people, they're just fun shaped targets that spit out points, and we like it when we're told "well done"

Man I could play Carmageddon 2 for hours. I miss that.