I can't remember that I ever provided it but I heard this a lot. They say that it significantly lowers fraud rates. It's not a legal requirement. Interestingly

I can't remember that I ever provided it but I heard this a lot. They say that it significantly lowers fraud rates. It's not a legal requirement. Interestingly enough, it's debatable if copies of state-issued IDs are even allowed in Germany (there were courts saying that practices like this are illegal). EDIT: apparently that's legal now, see the answer below. I don't like the practice but believe their argument, hosting services attract a lot of bad actors and this will probably filter out most of them from the start.