How about lettuce, carrots, eggs, etc? Just because their reaction times are slower does not mean they are not suffering?

The truth is humans are wired to gauge the level of environmental danger by looking for personably relatable aggression events. And there is a practical limit how low we should go. Also with living more dense, humans are gotten way better at handling various aggressive stimuli, like noise, air pollution, constant close interaction. We have stopped treating them as aggression, but it still is for the rest of life on this rock.