I do agree that there are not always "obvious" disabilities for those with service dogs and that many of the laws/policies (in the US) are oppressive to dog owners i.e. you can be cited, in many jurisdictions, for leaving your dog in the car, but you can't bring them into the store either, or leave them tied up outside. But my OP was in regard to someone I have known for many years, and though she is getting on in years, has no disability, and the dog is not certified, just well-trained. I find this kind of abuse of 'the system' and of people's general kindness to be just wrong.
Relating to handicapped parking, I would rather walk from the furthest parking available than park in a handicapped designated spot. My father has a handicapped hang tag (hip and knee surgeries) but keeps it in his glove box and only uses it if he's having a "bad" day.
BTW: Kipawa - don't know where she got the "service dog" vest, but probably not e-Bay as she is not very 'computer savy'. I suspect from someone who actually has service dogs. Which, in and of itself, is another problem.