Almost all of us. We do not question why we stop for the ducks crossing the road on our way to KFC. Why we pet calves at the petting zoo and then stop by the hot dog stand for lunch. Why we sit on a couch and watch TV with our dogs while we chow down on a pepperoni pizza.
In fact, many pet owners consider themselves animal rights activists. A lot of them have boycott SeaWorld and other exploitative establishments. Many are against hunting, or wearing fur, and consider themselves knowledgeable about animal rights issues. They would be horrified to see hidden footage taken from inside factory farms.
Most of us justify meat eating by saying that rearing "livestock" is different than rearing pets. It's horrible to beat your dog, but livestock are systemically exploited. It's okay because it's regulated. When abuse does occur, these are one-off cases. The solution to stopping animal abuse is to treat our livestock more humanely, but not to stop eating meat.
These justifications ignore the fact that there is no humane way to kill. In a system where animals are raised for slaughter, these animals will be mistreated, and there is no amount of regulation that will stop it. The system cannot be fixed. It needs to be dismantled. The only difference between the pet cat in your lap and the steak on your plate is the social acceptance behind eating that steak, which gives us the false sense that what we're doing must be okay.