Cats need to be taught by their mothers. And a second thing, is that some cats really respect the home and the humans more than you think.

Our late Oreo was an amazing hunter! She caught everything. Once they were inside however, she often lost the nerve, and we had to deal with it if they were still alive...we have 2 nets for this purpose, which are lying fallow now.
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Something about the "prey" being inside means it belongs to the humans now???

We gave Maya a dead mouse Weezie had caught outside (Weez does not eat them). Maya was on the screened in back porch and boy did she react to that mouse. Growling, carrying it around, licking it, etc. After about a half hour hubby took it away... as she lost interest. She sure reacted to that! Maya also likes feathers. Sometimes we find an exploded bird--- hawk handiwork-- near the bird feeder, and we bring the nicest ones in. Maya had 2 of these feathers for over a week. She LOVED them.

I think cats that come from highly indoor or domesticated lines, are less smart about prey. The ones we've adopted from stray mothers, or these 2 ferals...are very very different.

So I don't think it is exactly being dense or stupid...I think it might be blunted instincts because of heredity or lack of experience. Weez has become a moderate hunter outside, but does not eat her catch. She brings it home for us to admire.
She really liked the pigmy shrews upNorth.... they are fast and a challenge!