Why would someone want to eat the poop tube or liver of an animal?

Let's face it, people are disgusting. 

That's part of the deal when meat is hard to get, they use everything but the oink. And when times are good, it's tradition!

 Pretty gross. Eck. I don't eat any guts but I have tried liver and it is really disgusting. Haven't ever eat poop tube unless it was mixed in with the hotdog or bologna. 

To put things in perspective, alcohol is yeast poop. Air can be finagled into being considered tree poop. Camel crap is a medicine in parts of Arabia. And most importantly, our crap is the main food source for some bacteria and scavengers. There's even a dish where, I believe goat, poop is cooked into a soup because it's just fermented grass.

We have evolved to be disgusted by our own species' poop because it is what our bodies want to get rid of. As we've just discussed, the poop of some things is exactly what other things want to take in. And that said, intestine and liver don't contain poop or things the chicken or pig was getting rid of... assuming you clean it right. They are just tools inside the animal as much as the muscles are.

They didn't want to. They originally had to make due with what they were given. Through the generations, tasty ways were found to prepare garbage and it became acceptable, if not a delicacy.

that's very horrible pop tube

You are maybe cooking the liver wrong.  

That's part of the deal when meat is hard to get, they use everything but the oink. And when times are good, it's tradition!

some of its traditional food from their home country

When the alternative is starving to death, you adapt. 

Is that any worse than eating it's leg?

That's disgusting according to you and an insult to those who do. Why would people eat the flesh of another living animal, that's just cruel and gross. All that blood(myoglobin) and sinew, it's another living animal, how could you!??? Hearing that cartilage break when you are eating chicken wings is horrible. The rest of the world spends billions on developing biological weapons and the Swedes have Surstromming. I'm gonna go cook some chitterlings now.

Generally, people do not eat the intestines ['poop tubes'] of animals, except as emergency food in times of famine or war. Otherwise, it is used to make pet food. Liver, on the other hand, is delicious with bacon, carrots and onions in a casserole.