Too many eager to play doc or cop
You do not know what the disability of others are. Just because you do not see an apparent disability does not mean that one does not exist. Anyone with physical difficulties knows that at times you may feel able to walk around "normally." By the time you complete your shopping your situation could change to were you cannot make it to the check stand, let alone your car.
It is none of your business what disability others have. You are not their doctor, so it is not your call on whether or not they are abusing their "right" to park in those spaces. My husband and I have had many nosy people yell at us to explain our disability because they did not feel that we were entitled to park there. We respond to them that they are not a licensed doctor and it is none of their business.
Contrary to the belief of those narrow-minded individuals, doctors do not hand out those permits like candy. Red permits are for a temporary disabilities and blue permits are for long-term disabilities. The doctor, upon evaluating the patient, determine which permit their patient should have.
We know all too well how much of the police departments time is wasted (they do to respond to complaints about violators) responding to those nosy people. Even the police do not ask what our disability is because it is none of their business. They check out our ID cards and apologize for having to waste our time.
A good solution would be to contact the business to see about having enough disabled parking spaces made available to accommodate all of their customers. If enough customers request it they will realize that the need is there. Accusing people of being law breakers is not the solution, not to mention a waste of police department resources.
So the next time you have to wait for a disabled parking spot do not judge others by your own non-medical standards. They may have a good reason to be parked there and chances are they had to wait to get that parking space as well. So do not embarrass or challenge others because you think that you are more entitled to park there than they are. Heaven forbid you could be wrong.