I think that there are many people who would qualify for parking permits who don't get them. As a door greeter, I see people hobble in with great difficulty from some distance away from the store. They can barely make it, but they do it each time the come.
I think some people are embarrassed to have a parking permit, while others think that as long as they can do it, no matter what the cost in energy or pain, they won't get a permit.