Generally they want a doctors note and in a case like your dad's his Dr probably wouldn't have an issue with writing one up. We got one from the doctor who operated on my wife's leg (had to ask for it, but he had no problem writing a note for a tag), I plan to take it in to the town clerk this week and getting a tag.
Aaron Z
In Tennessee, you must have a DMV form signed by doctor. Also, it has box to check for permanent or temporary (6mo) tag. Temp is a mirror hanger that is red versus blue for temp, and has the expiration date on it. I got one after knee replacement.
Local city also has a guy on full time handicap duty, checking tags, mirror hangers, etc. He will even write up folks if they park over the handicap lines a shade !
They probably DO issue too many tags/hangers.....but the requirements for businesses having handicap parking gets kinda stupid too.
For example, we have a local fast food chain that is strictly drive-thru.....no inside dining, no restrooms, no outside tables....nothing....just drive in one side, pay, drive around the other pickup food. They do have 3 parking places so you can pull on up and eat in your car if you want (99% drive on out)....
not even an outside trash can to put your food trash in.....and one of the spaces is marked for handicap....just because the local requires a certain % of spaces to be marked handicap.....remember, absolutely zero reason to exit the car, so handicap doesn't come into play.....just has to be, because.