Although you may think that it's the training and practice in the aircraft that gives you the proficiency to fly at night, the CAA knows better. It's actually the possession of a poorly printed piece of paper that ensures safety, and this is why you can't fly until they print it out and send it to you.
Of course, in the USA they issue a temporary licence there in the spot after you pass a flight test, but in Europe this would just be terribly dangerous
