Stores are afraid to do anything for fear of being sued. I've seen ESA owners get media attention when turned away, forcing the companies who were within their rights to back peddle for fear of losing customers. 
 Almost every media story i've seen recently is either an ESA or total fake dog with "certification" papers who refused to answer the store's questions. Whoever is supposed to be going after fake dogs on a federal level should just search " service dog denied" and they'd have a good starting place.
I've suggested to the Justice Dept a Federal Disability Cert Card  that physicians can give to people who meet the ADA requirements as Disabled and need a SD.  At that point the dog is medical equipment as designed without disclosing any personal info and stopping people faking disabilities in their tracks. Instead of asking the 2 questions stores simply ask to see the card. At that point, all dogs get turned away if the card can't be presented. Please do the same if you like it.