Most likely because if a cat gets ran over if they aren't killed it would be expected that they get a broken leg/broken spine/other serious injury/disability that would cause them to go to the elders den
Broken spine, sure. Broken or missing leg, or blindness like the game sometimes gives? Hell no. Real cats can thrive perfectly fine without sight or even without two legs. ESPECIALLY in a clan where they have magic cat doctors with magic medicine that would normally kill a cat irl.
And paralysis would kill the cat since paralyzed cats can't ahem... make dirt on their own or would leak 'dirt' everywhere. Also the broken spine bones could pierce internal organs killing the cat