This question is aimed at a very specific view point. Not everyone that eats meat has the same reasoning as to why.

To answer your questions about comparisons of humans/non-humans, I think one valid point against that comparison has to do with racism. Historically (and still today), people of color (particularly black and indigenous people) have been compared to animals/"less than human". So when people say things like "how is dairy ok but human slavery isnt" or, " meat eaters aren't any better than nazis", it's like you're putting those groups on the same level as animals.

For someone that 100% believes humans and animals are completely equal, this may not seem like an issue. For some of the people in those groups, however, it's a lot more real and less about moral hypotheticals/ideals.

I know your questions doesn't make those same comparisons, but the questions is about general human/animal comparisons.

To speak to your questions specifically, at least some meat-eaters (myself included) feel that some types of non-vegan food consumption do not cause harm, or that the harm caused would cause less harm than consuming the vegan alternative.

Next time you see someone eating banana vegan ice cream, or cooking with coconut oil, ask them why they think it's OK to participate in pesticide use, monoculture systems, worker exploitation/corporate terrorism on small farming communities of color, fossil fuel emissions/plastic pollution, but not to abuse a child.