The most common issue stems from the consciences of many meat-eaters. This is what precipitates the lectures about protein intake and the sermons about how "God" put select animals (which are dependent upon cultural norms, strangely enough) on earth for humans to eat.
There are some carnivores who genuinely don't care at all about animals and merely harass vegetarians because it's fun, but they're extremely rare. I've found that it's usually people who do care about animals, but only certain ones. They wouldn't dream of eating a domestic dog or cat and think that the people in certain Asian countries who do are barbaric monsters, yet they chow down on pigs, despite them being more intelligent and every bit as sentient as dogs... because bacon is yummy.
I never dreamed that becoming vegetarian would have given me so much insight into the nature of other humans.
