Locksmiths in Germany do not reproduce keys just like that; some keys, with intricate patterns of grooves and ridges, or with identifying codes on them, proving that they belong to a system, are rejected. The locksmith tells you either that he can't do it, because he does not have the blank prototype, or that he is not allowed to. It was not like that in Turkey when I was growing up; take a key with you to a locksmith, and he would reproduce it with a very simple device in a matter of seconds, for very little money. But the keys there were also much simpler; two or three ridges, some teeth and dents. It was not unusual that a key opened many doors, sometimes unexpected ones. You would confuse the floor you are in, and try to open what you thought was the door to your home, and land in the entrance of a foreign one; your key opens your neighbour's door.
I stand inside a locksmith's shop. The register has a glass top, and under it one can see hundreds of discarded keys. From above the counter, their only difference appears to be the color and rustiness of the metal, also the size differences of very small and very big keys. Discarded keys which used to open a door somewhere. Maybe they still do, but we don't know for sure. Maybe they can open doors which they were not intended for; one thing we have more than lights and windows is doors which can be locked. Every house has them, every apartment, and most bathrooms and toilets.
If I could look closer, I would see so much more, but I don't have the time. Not the time to look, but the time to take it in, to think about it. I get out of the shop, with my unreproducible key.