The best public option to control feral cat populations is with a no closed season, no limit on their taking, not TNR.  Feral cats (neutered or not) do incredible damage to wild songbird populations.  Why anyone would encourage their feeding is beyond me.  If you are a farmer who needs barn cats, please neuter them all.

Read up on the parasite Toxoplasmosis and how many cat people are infected with it.  Perhaps that's what attracts them to feral cats.