I work at the DMV, and dispense the placards. I once had a lady (maybe 30?) who told me horror stories about being physically threatened because she wasn't old, and therefore didn't need it. Her disability? Congestive heart disease.
On another occasion, an older woman didn't see why we wouldn't just give her one, because they "were a courtesy that we issue to senior citizens." No, ma'am, I am sorry, but age has nothing to do with it. The issue is strictly whether the applicant has trouble moving from a parking spot and into a building.