Asking out of ignorance. Why is the liver thrown out? Isn't it edible too?

I like cow liver, it's nasty to handle while raw, but I like it cooked in thin beefs with fried onion.

I also like chicken liver. It's small enough to be cooked whole.

I'd like to try pig liver.

Who would eat it these days? The same with e.g. sheepskins. The labor to process them in western countries is so high so they generally just get thrown away.

I was under the impression it went in to livestock/pet food. Perhaps there just isn’t enough demand.

Does the same apply to offal of other animals? I thought that liver didn't need much processing. What am I missing here?