I could easily imagine this happening if they have two separate layers of availability checks. One general authentication check (likely with coarse "DVD region" baked in) owned by one suborg and another to handle all the eccentric subtleties of hundreds of different licensors owned by a different suborg. As laughable as "security by hiding the UI" is, when it's only protecting licensing nuances that have traditionally only been enforced by broadcast range (which is roughly continental for satellite) pressure to fix it can be very, very low.

Here in Germany violence in video games used to be heavily censored. Much less so now, but when I was growing up, you basically couldn't have blood in games. I remember playing a GTA game that had bleeding NPCs or not, depending on whether you selected German or English as the game language.

The hoops are documented: https://help.netflix.com/en/node/13245 ("Change your subtitle language" section)

It says "Due to the large number of languages available, Netflix only displays the 5-7 languages most relevant to you while streaming." and then proceeds to tell the steps to change profile language to get other languages.