Octopuses, crabs and lobsters to be recognised as sentient beings under UK law

This is easily refuted by the myriad instances of animals escaping their captors, strategizing, and even empathizing. For academic writing on exactly that, I suggest reading "Animal Resistance in the Global Capitalist Era" by Sarat Colling.

In the same way, creating unnecessary suffering also creates sadistic societies that lead to a lot of harm.

So there is a golden mean in which a natural amount of suffering is recognized as the price of life - we will all suffer and die, but in exchange we can also live -- and people have historically been mature enough to accept that and decide the combo of life+suffering as better than the combo no-life+no-suffering.

Specifically for the case of livestock, none of those animals would have been born if they were not going to be eaten, so for humanely raised animals, the suffering imposed on the animal when the farmer sends it to slaughter is not so great as to outweigh the life given to the animal by the same farmer. This can be viewed as the definition of humane animal husbandry.

Of course there is a lot of animal husbandry that is not humane and this type of animal husbandry is unethical. That's why there is a big movement for full pasture-raised beef and grass fed beef without hormones, as well as pasture-raised chicken, etc.

Similarly for the hunter, killing the octopus or salmon or deer is not worse than some other animal doing the same or the animal dying of some other cause, so there is not a net increase in suffering for the animal's life simply because a human eats it as opposed to some other animal eating it.

This of course depends on the ecological system being in balance. Killing an animal takes away one meal from its predators but also saves the lives of its prey. An ecological system is in a steady state when everything eaten is replaced so again suffering is the price of life within a balanced ecology, and that ecology includes human hunters.

By the same token, overfishing or overhunting that drives animals to extinction is also not humane, while hunting and fishing that does not is humane.

By the way this is why vegetarianism in western societies is primarily practiced by younger people who feel as if they are immortal and aren't really faced with the understanding that everything in life must be paid for with suffering and death. They view suffering as strange.

Others do not, and that's the dividing line. It's not that people don't care, they just aren't convinced that hedonism is a basis for a healthy society and they look for a wiser, more balanced ethical system that values life with suffering, and that includes the life of animals hunted or raised for food.