Because
millions of pets are killed every year, most having been abandoned and/or abused. Or they're the result of irresponsible owners who failed to have the parents spayed or neutered. Or they're rescued from dogfighting rings, or from living their entire lives chained outside...regardless of weather. They end up being killed because there are too many of them.
Tried to have a decent chat with this, with my mom, and against all thinking even more of religions too, I think there is always something more shifty to her own mind . But hey once the ARRP rolls her into a nice home, with a window to look at her garden, she will really appericated the matter of her own mind too.
I am a big picture kind of guy too.
Rescues/shelters, through their vetting process, seek to find loving, responsible pet parents who will provide a
forever home, with regular medical and other care, and who will treat the pet as part of the family. That's a good thing.
The vetting process may seem like a pain, but it's a win/win situation when the right pet and right parents are united.