And before you refute that it's just for digtial downloads, it's very likely an immediate ban would happen for physical releases. Since they solved the issue of trading game headers.
That was the main issue with CDs, when you make a CD you create a master and then duplicate it thousands times so they were not able to forge a ticket per disk and thus we were able to use those on any Wii U without issues, but the main issue is that because it worked that way for CDs they did the same for e-shop, so no ways to check if a tiltle was legit or no.
With cartdriges it's really different, you can always find a way to copy a disk, a magnetic tape etc, but with a SOC it's really difficult (possible to clone but difficult) and they are able to set a unique ID, cert and key inside each chip and then check if it's used twice at the same time and I'm sure it's what they are doing, but because you can play offline they got no ways use dynamic encryption to secure their cartdrige with their servers (it's possible but you lose the offline ability)