Couple of clarifications.

Airlines are not simply "okay" with it, unless you mean that they are not using their legal rights to restrict emotional support animals. Also, airlines cannot charge for the animal to ride in the cabin, so the extra $100 is a myth. It is also why many pet owners try to go the service animal route--free passage for their pet.

I just asked this question Monday on a Southwest flight as there was a dog in the cabin--not a service animal, an "emotional support" animal--there is no additional cost for the animal to fly in the cabin if designated as either of these, and animal must sit in passengers lap or under seat, but a carrier is not required.

Ok sorry I thought people were paying for it.

that is the type of BS being discussed by the OP. True "service animals" are specially trained. Many(not all) of the "emotional support" animals on flights are simply pets that inconsiderate owners bring into the cabin because they don't want to pay to bring the animal onboard and keep it in a carrier, or pay to check the animal. Flying is irritating enough without having to contend with an ill-trained pig.

Just saw a whole new one. A woman walked into the grocery store with two dogs, one with a service vest. As it was dark out and I saw her in the parking lot, I couldn't really see if the other dog had one on. I don't know why the store puts up with that. It's obviously a fake. I'm sure the crowd doing Thanksgiving shopping loves having untrained dogs running around them at the store.

''This here support pig saved my life !''

''But why does your pig have one leg ?''

''Well, with a pig like that, you don't want to eat it all at once.''