"Why is there no queuing system in the carpark?"

We drove to the hospital yesterday allowing a hour to park and find the correct department. We hoped for a disabled parking space as I have breathing difficulties. We looked for any space as the disabled were all taken but were unable to find a space. We drove around and around. We told the staff in the car park that my appointment time was near but they allowed a car which had only just arrived to take a space which was vacated. As a result I was not able to keep my appointment. This situation is ludicrous. Why is there no queuing system? At least if there is a queue drivers know that as the spaces are emptied they will get a space in their order of arrival.