Every router I've ever seen has a pretty clear setup option for creating a hidden network. I agree that defaults are powerful, but they don't make it any less "willing," they merely expose people's indifference.
I'm making a general point about identifiers and protocols. The same thing applies to client MACs, which are obviously being used to track phone users with wifi on. Obviously MAC addresses can be cycled, but that takes active diligence. If the protocol had simply been designed to eschew and hide such identifiers in the first place, the entire issue wouldn't even exist.
I've never heard of this, and have family that served in the Pacific during WWII. I'm also having difficulty discovering any sources that mention the practice, let alone reliable ones.
AFAIK, it was never policy of the Allied forces to tattoo anything on captured POWs. I would be very surprised if captured Axis soldiers were not given some sort of uniform, unique tracking number.
Hidden networks are even less private, because then every client device has to probe repeatedly to see if the network is there.
The useful parallel is the general inventorying and tracking of people. Luckily we don't have the rest of totalitarianism (yet), but this cornerstone is well laid due to naive designers.
BTW you were the one who brought up the subject of Nazis.