Why a lot of people don't care?

Yesterday, my husband & I saw a program on T.V. where they started to peel an Eel mean while it was still alive, as if this animal didn’t suffer. The chef in the program took the animal from a container with water and started to peel out the skin.
It's unbelievable how people put limits to animal suffering randomly. Where is the limit of animal suffering? Why do people consider one animal more than another one when it comes to suffering, to feel pain, to cause it or to avoid it? It seems that a lot of this has to do with the culture that you are immerse in. Depending on the culture some people seem to care more about certain animals than others.
In South American countries for example they eat all type of animals, and they don't usually care about the conditions that they are raised in nor the way the animal is cooked.
Here in North America it seems to be clear that people mark a line, a limit to animal suffering when it refers to dogs & cats, which both are under the category of domesticated animals. Although, when we think about domesticated animals why don't we feel the same compassion for animals such as chickens, pigs, cows and turkeys? What and who determines which feels more pain? Where should we draw the line and not care about the animal suffering?
These types of subjects and concerns are well treated by authors like Peter Singer & Jesús Mosterín. Both of them are well-respected philosophers who are dedicated to examining the conditions that animals are put in by humans.
One of my main concerns in life is how animals are treated, how they are raised, in what conditions they live from the day they are born until they die. That's why I'm concern about INDUSTRIAL FARMS. Concern about how people raised and kill the animals for food and/or for comfort and luxury. Concern if the animal suffers for a considerable period of time before it actually dies.
Even though I don't share the eating of animals I still believe that those people who do, should be aware of how the animals are raised and the way that they are killed. The less suffering during their life period and the less suffering during their death should be something to keep in mind because ultimately ALL ANIMALS (including US) have the capacity to feel pain and the wish to avoid it.