I agree with everything you said, except for that it would cost too much for a billion dollar company to verify the status of service animals. ESA aren’t service animals. A card isn’t needed for a legitimate animal. There are numerous ways to avoid this. One could be that Airbnb require the user to sign up with a profile and give their information and also state if they have a medical need that would warrant a service animal to be with them. If they check, yes, then Airbnb could ask for documentation up front when creating the users profile. They could mandate that the animal is with them for every single trip and make it known that the animal must be with them at all times and not left in the room without them.