Note: I think I might have encountered a way in which NOE is distinguishing itself from the other regional subsidiaries, as I could not see this problem raised by U.S. owners or JPN ones (the system is not even out in that region).
A few days ago, the thread starter here managed to destroy part of the PIN for NSMB U so I could not register it on my Nintendo Club account here in PAL land. I have the receipt, I have the game case, I have the PIN card slip with a bit of damage, but mostly in good conditions. So hey, let's scan it all and see if Nintendo's customers support could help me recover the code (and they did, so kudos to them as they kindly sent me the whole PIN number back in an e-mail... just telling this if you want the full story and would like a jab in the vein of "bite the hands which feeds you eh?").
I decided to also try to get another answer from the same message, I added a P.S. inquiring about my problem with the eShop. I noticed I could not access some sections of the store and I found it weird. Nintendo's Customer Support did ask me to explain the problem in more detail, so I replied with the exact message I could see on my GamePad when trying to access the Zombie U page.
I had found this thread on NeoGAF (http://www.neogaf.com/forum/showthread.php?p=44986488
) dealing with it, but in the middle of the jokes about the OP's age the only thing coming up was something like "problem with their servers, must be a launch thing...".
From the series of e-mails I have exchanged thus far, it turns out that no... it is not a glitch in their system, but a purposefully built filter to add another layer of protection to minors, so that they can be protected from watching bad sections of the eShop targeted at adults.
"Won't somebody please think of the children?"
Here is part of the exchange of e-mails (the following images have been uploaded to Imgur, so I hope they do not disappear soon):
Quick translation: "Dear customer, we would like to let you know that Nintendo has always aimed to offer gameplay experiences suited to all age groups, observing carefully all the relevant regulations regarding content access that are present in the various European countries.
We have thus decided to restrict the access to content which is unsuitable to minors (PEGI) to the 11 P.M. - 3 A.M. time window [...]"
Quick translation: "Dear customer, we would like to inform you that it is an additional precaution to make sure that minors cannot access content which is inappropriate for their age"
Note: my birthday is correctly set in my NNID account, I did mention this fact to Nintendo's customer support and I also specifically asked if this measure should affect a console with no parental controls or parental controls without restrictions (tried both kinds of settings). I wanted to make sure that it was neither a glitch nor something due to a mistake I might have made configuring my account. It turn out, as you can see in their answers, that not... it is part of a clearly stated internal policy.
Frankly, I think this is a paternalistic measure which does not instill confidence in their child accounts and the parental controls their platform offers. Also, it does not really respect me as an adult to be responsible and use them to make sure that a child (which my wife and I do not yet have) does not access contents which are not right for his age.