It literally can't be done, in Germany.

There is corruption in Germany, but it simply does not exist at this level. It also wouldn't work in practice: You would have to find out who is the office worker working on your documents (you usually don't know that, and never in advance). Then that person has safeguards: He is part of a team, someone will check his work, usually at least a colleague and his boss. Assume you'd try anyway, you meet the person somehow alone - how would you find out whether he is corruptible? If you try to ask you will face severe consequences.

Plus, it's never worth it for him: If they were caught they would be facing jail time, lose their job, all the benefits already earned (the special pension state servants get, their health insurance, ...). You'd have to offer that much money that all of that is worth it. Not even twenty times the money we are talking about here would be enough.