Oh my god

Cats and humans have gotten along for millennia, spaying and neutering them only started to become common in the first world in the 1970s.  (Which means when Bob Barker started ending Price is Right episodes by imploring people to spay and neuter their pets, it was still novel.)

Part of it’s back when the world was a lot more agricultural, cats tended to be considered more “allied local wildlife” than family members - you’d never even think of neutering the squirrels in your trees, would you? And farmers are not squeamish about killing animals for practical reasons.

Killing surplus kittens was considered a matter of proper, pro-social animal husbandry and “tied-off sack in a pond” was a well-recognized trope for this.