People that defend the Carnivore diet, argument that plants don't want to be eaten and because they lack locomotion to run away but are excellent at chemistry, have developed toxins to protect themselves from predators.
Toxins that bioaccumulate either are produced outside and don't work well inside a biological system (heavy metals, etc) or are fat-soluble
Easiest for plants to do is make neurotoxins as they don't have a nervous system to get bothered by it. But those are usually water-soluble.
Carnivore stomach is short and very acid to be able to dissolve bones and horns. Most complex molecules wouldn't survive to be dipped in acid two times in two different stomachs and be taken in the intestine by the blood vessels later.
Terrestrial mammals are safe to eat normally if not rotten (not so much safe to kill them). Plants are unsafe to eat by default, except domesticated species and some wild species. Ripped fruits like 50/50, often safe to eat but not always.