It's a fine line, isn't it. It's interesting to speculate why we find pointless cruelty repulsive, but not meat-eating.
Bear in mind that many people do find factory-farming repulsive - that is, the wanton cruelty involved in raising and killing the animals, as opposed to the actual meat-eating part. And they do protest about it. But then along comes a government guy with a clipboard and says, move along people, nothing to see here, it's all lawful. Which it is. Because clipboard guy says so, even though according to the letter of the law it probably isn't. Horrible things happen to the average Large White destined for bacon - things that would be 100% illegal, and prosecuted as such, if they happened to a pet teacup pig. It absolutely is insane.
Actually it's a bit worse than that. In the US at least, it's basically illegal to raise a small herd of pigs, treat them kindly, and slaughter them yourself as humanely as possible ... at least if you wish to sell the meat. Reason being, you have to have a six-inch high stack of certifications to operate a slaughterhouse, plus an inspection from the gubmint when pigs are going through the line. If the inspector doesn't want to turn up (which he won't if you're processing four of five pigs) then he won't turn up. Your operation becomes de facto illegal and can be instantly shut down. A lot of small operators, who set up with the explicit intent of providing a cruelty-free service, have been quietly put out of business via this gambit.
Anyway, I think the point here is that we do (in theory) aim to kill a meat pig quickly and without suffering. There is (in theory) no malice or enjoyment in the act of killing. Humans are omnivores. We eat meat. I think most people would prefer their meat to be cruelty-free. It's just that governments, mostly, encourage cruelty in the name of "efficiency".