TNR works absolutely fine at reducing feral cat populations. The issue is not that people are not killing enough cats, it's that getting a cat spayed or neutered can be expensive and therefore inaccessible to a lot of people, and a lot of dickhead liberals just expect poor people to not have pets if they can't keep $10,000 USD in the bank at all times to cover emergency vet expenses (legit shit you'll see bandied around as advice for "responsible" owners). An effective response would be offering free spay, neuter, and chip services for all pets, alongside people keeping their pets indoors, and maybe offering stuff like pine litter for free to address some reasons why people might want their cat to be outside.