[rendx]

It's a mistake to assume courts need "proof" for a ruling. It's totally sufficient if courts find that it's just the most likely. "Not guilty until proven innocent".

If you receive child porn in your mailbox and the package is caught, you better have a really good story. Like, prior documented proof of harassment.

In regards to your question, and Germany specifically: Media companies hire specialist lawyers. These lawyers prefer to sue in Hamburg, where the courts are known to be very media company friendly. It's just not likely that you ran some experiment and didn't upload anything, so you better have it documented well enough to convince the court.

[pocksuppet]

What happens if someone puts child porn in 100 random person's mailboxen, and does not get caught?

[rendx]

Well what do you think would happen?

I would think that at least a couple dozen of those 100 random people will report to the police. These reports can be used in court, and may or may not convince the judge that you're also one of the victims. You'd also think there was other circumstantial material to be used either arguing for or against.

Compare to torrenting: Not a dozen of 100 people will independently and proactively report that they ran some "experiments". You're on your own with that story, and it sure sounds like an excuse (to me) even if it were true. Plenty of people end up in jail (or with fines) being innocent. Real world is not the movies. Real courts do not need 100% certainty to "prove guilty according to law".

https://en.wikipedia.org/wiki/Reasonable_doubt