I agree with you but sadly training on ESA vs Support animals (which since 2010 can only be dogs) is rare, and just cause the (often fakers) to get upset and throw a scene which corporate doesn't want (and in the rare case it is legit if done the wrong way opens them up to lawsuits / Civil Rights violations) and will just cause a shit fest on twitter (or worst national media) because people are exceptional.You can't ask for papers, but you can ask two questions:
1.) Is this animal required for a disability?
2.) What has this animal been trained to do?
More cons need to ask those questions, and ask handlers to remove misbehaving animals from con space.