Saturn data protection?

I ordered a ps4 game from Saturn and when it arrived today the postman didn't want to give it to me because he said he had to give it to someone who is 18 because the game is from 18 and I'm only 17. But why does the DHL postman know what is in the package, that is full of the data protection violation or not

Can someone explain to me why they know that

Who doesn't know what's inside. But he can read what's on it. And there's certainly an age rating on it only from 18.

It was sent via age verification; that is what Media Markt initiated. The recipient must be at least 18 years old and identify themselves with their ID. No one else can receive the package.

How do you come up with data protection?