Service dogs
Emotional support dogs are not service dogs per the ADA and ought not be afforded any privileges on planes. Service dogs must be trained to perform a function. Being a comfort is not a trained activity, but is inherent in dogs.
Given the abuse of service dogs, and the fear of inquiring (one can legally ask what a dog is trained to do), we have a major gap in the law that would balance the rights of the public to not be subject to fraud by a growing group of abusers.
What will likely happen in the near future is someone saying no to a suspect dog and owner, being sued and a court weighing in and providing guidelines.
Certification can be bought online for a dog and there is no central authority for proving validity of such a claim. That is the problem. And the general public likely can't be sued for calling someone out on their fraud, only a business who says no. Most of us have no problem at all with a well trained seeing eye dog for example. But the lies and deception that likely are behind a majority of so called service dogs calls out for a legislative or litigated solution. And to be clear, emotional support while compelling, is not a service dog. I have an emotional support wife. By that criteria, she should be able to fly free to accommodate my fragile self.