Do you seriously think Audi would let thousands of cars out with such an obvious design fault? The switch doesn't switch the DRL circuit on/off, it simply changes the signal to the Central Electrics module, which will always kill the circuit when the ignition is off. The facelift cars don't even bother having the switch, so if there was any problem with leakage current we would have heard of thousands of facelift cars being stranded with flat batteries by now. So as a rough guide in these situations, refer to my first post.
I hope that's a little more helpful for you.
(besides, you're the one the said it was probably a daft question)