Plain and simple, people have the ability to ignore things that are unethical if they consider the benefits sufficiently important. If you are reading this, you are using a device that is the result of thousands of hours of actual chattel slave labor, conflict-producing minerals, assembled by workers in horrific conditions. And yet you use that iphone or thinkpad.

Any person living in the first world is the beneficiary of an immense amount of human suffering and cruelty, period. There is no way to avoid it short of living a hermetic life in the woods. So why don't you do that? Because society is convenient and nice to live in.

People eat meat because it's delicious. People buy factory-farmed meat because it's cheap and they can use the money they save on something else. People use smartphones and PCs because they're entertaining. It really doesn't seem like a deep question to me at all.

As for why people who live on farms, specifically, would be more likely to eat meat... I suppose people probably become desensitized to it, the same as someone who works in Foxconn would become desensitized to what we would perceive as human suffering.

I dunno, it doesn't really seem that complex an issue to me. Pete Singer is right, the ethical answer is to reduce our suffering footprint as much as we possibly can. But hedonism is so damned pleasurable, that people won't. If you can moderately reduce your suffering footprint in a sustainable fashion, like a diet, by something like veganism then go for it, but you also can't reduce it to zero.