My cat hunts bugs. She catches them, she plays with them, but she
never kills them nor eats them. I always attributed it to lack of
training. :)

Actually, most cats have to be shown how to kill. Some do learn by
accident. Most cats will play with rodents, but most do not actually
kill them.

And it isn't about whether they need to or not. Chase was adopted as a
kitten, but was outside before we got him. Both parents were barn cats.
He has been indoor only since then. But he knows where to go up into
the ceiling to find a nest of rats. And several times a year, he brings
out the babies, one a night. He does like to play with them, so
sometimes they are still alive, but he does kill them if given enough
time. And he will eat them. One time, I found just the head.  My other
cats will play with one and show interest, but they don't hunt as
seriously, nor do they actually know what to do with one if they get
it.

We have had many cats over the years and two have chosen to hunt, kill,
and sometimes eat their prey. And these are indoor only cats. They
certainly had no need to hunt, and haven't since they were kittens.
They simply had more drive to do so.

Just as some breeds of dogs are known for high prey drive while others
are not.
My neighbor used to have a husky, and while that dog was well fed and
had no need to hunt, he would go after anything that moved. She made a
point of checking her yard for cats and squirrels before letting her
dog out in her own yard. And once while on a leash, the dog saw a cat
before she did. She was injured in her struggle to get her dog off that
cat. She loved her dog, but she said she would never get another one.
It was too much stress worrying about the other animals.

I would think that barn cats would naturally be better hunters simply
because the instinct has to be strong to survive, so they pass it
along. But even so, they would need to be shown. Maynard was half
barncat, and he never killed anything. Chase them, yes. It was kinda
funny last year when Chase brought in a live one and released it on my
bed. Normally, I would not think that funny at all. but Maynard (at age
18) jumped up in excitement and almost got it. You could see the look
on his face (ooh! live toy). He was like a kitten again.

All that said, I don't know why anybody would want to teach their cat
to hunt if it is an indoor cat. I certainly wouldn't buy rodents just
to use them as bait. That seems cruel.