Well the laws here are really stupid. ESAs are not covered under federal law. But service animals are. However - there is no accreditation program for service animals, so you cannot ask for proof that an animal is a service animal. You are also not allowed to ask a person what their disability is or demand they demonstrate some sort of proof of either disability or specialized training in their animal. So essentially, anyone can still claim any animal is a service animal and the airlines have to accommodate them. The ESA designation is NOT a service animal (although a service animal can also be an ESA). So this is something the airlines could easily disallow. I'm afraid we haven't seen the last of people abusing the system for their own convenience, however.