What do we do if a policeman challenges us and we say we are exempt? Do you have to say which exemption you are claiming, I would use "severe distress". Do they have to just accept your word and could they demand you give further details as proof?
If they decide that they don't think you are exempt under "severe distress" and issue you a penalty then what happens? I assume the only way to avoid paying it would be to go to court and argue your case there. However, like many parking ticket cases, the cost in time and money involved would mean few would do so and end up agreeing that the penalty issued was justified. Hardly a fair process if that is the case since they could just issue penalties on the basis that most will end up paying.