"A kid could break into the mailbox" is one of the most inane reason for a law I ever heard. So it would be my problem if my neighbours kid is a thief? The law has to provide for that possibility? Guess I shouldn't have alcohol in my cupboard either. A kid could break my living room window and get drunkon my couch!
It's inane but has been used by a german judge to kill the online age verification scheme of an online video rental service.
The law for the protection of minors ("Jugendschutzgesetz") states that unrated material or material with a rating of "adult only" may not be sent per mail because the retailer cannot verify if the purchaser is an adult or not. The law was introduced long before the internet was invented, and computer games or splatter movies came into fashion, it's meaning was to prevent porn distributors from sending pornographic material to minors (and probably to prevent them from sending porn to anybody this being the fifties).
This meant that until a few years ago online or mail order retailers for games or movies only had things up to a rating of "suitable for ages 16 or above". With the advent of the internet and some modifications to the law online retailers extended their stock to include everything that was rated as "adult only" but people had to proof that they were of adult age before they could order anything. With automatic shop systems and user accounts it was no problem to restrict the online "adult only" section to only those people that had proof to be adults, so every part of the law was heeded. Minors weren't able to see anything concerning adult material (because the webserver wouldn't give them the relevant pages) and adults would still be able to rent/buy those things provided that they could proof that they were adults in the first place.
Then the first online video rental services came up. They did essentially the same, they had an "adult" section that could only be accessed by people that were verified to be adults. How that verification was done was different from site to site.
Some wanted a copy of your ID card per Fax or E-Mail.
Some wanted you to enter your Passport-ID Number (the age and date of birth is encoded into it)
The most popular service was something called PostIdent (Identification per Mail). The service sent you a form via snail mail, you would fill out the form and then you would head to the nearest post office were you had to give the post office workers that form and show them your ID. They could then ascertain that you are you and that you are of adult age and would certify that by signature and official stamp and would then send the form back to the retailer. The post office charges Eur 20 for that age verification service.
The retailer then could send you stuff via mail because he knew that the receiver was an adult person. Unfortunately the court doesn't see it that way. In a dispute between two online dvd rental services, the court ruled against all the age verification schemes mentioned above. He argued that all the age verification schemes can only ascertain that the purchaser is adult and even that might not be so sure because the user account and/or password might be known to kids living in the same household. They can however not ascertain whether the recipient of the package is adult. The mailman is allowed to give a package to other persons than the recipient or he might just put it in a mailbox where other persons than the intended recipient might take it without the knowledge of that person.
He ruled that the only legal way to send packages was as registered mail because when the package is sent as registered mail only the intended recipient is allowed to get it and he has to be present when the package is delivered.
This killed online video rental of adult material because a letter sent via registered mail costs up to $5 which they then would have to charge from the customers.
So nowadays most online stores do not offer adult only material (which would include things like reservoir dogs or from dusk till dawn or nearly everything by Chan-wook Park) because they don't like the hassle and those that do have to verify via PostIdent that the customer is an adult and need to sent everything via registered mail.