The name tags came about circa 2005, Global Game.
It was around this time that FIFA changed the structure of their women's age-grade competitions - previously, they had the U19 Women's World Cup, and the senior one. That became the U20 WWC, and the U17 one was introduced.
Up to this point, NZF had, on the men's side of the game, operated the Youth All Whites (U20s) and the Junior All Whites (U17s), those names reflecting the titles of FIFA's competitions in those days - the Youth World Championship was the U20s competition, and the Junior World Championship was for the U17s.
Now NZF also had this obscure idea, during this period, of reinventing aspects of their history. e.g. it was around this time that they were literally throwing out any number of old cups, trophies, awards, etc.. Thankfully a couple of us who value the history of the game in this country managed to retrieve things before they disappeared forever ...
I mention this because part of this rewriting of history entailed renaming their age-grade men's teams, which are now, in NZF-speak, the Junior All Whites (U20s) and the Young All Whites (U17s). And the age-grade women's teams were aligned with these, hence Junior Ferns (U20s) and Young Ferns (U17s).
Needless to say, I'm dead against this rewriting of history to suit certain agendas, and ever since this change came about have continued to refer to the age-grade men's teams by their original titles in any stories I've penned about them, qualified, of course, with their age-grade for clarity.
As their female equivalents didn't have name tags prior to this, i.e. they were always referred to as the NZ U19s or NZ U17s, I've no such issues where the use of Junior Ferns and Young Ferns is concerned. But being one of the very few folk still involved in NZ's football media today who was covering the game here when we hosted NZ '99, the FIFA U-17 World Cup Finals, when the NZ U17 team was correctly referred to as the Junior All Whites, I'm probably a lone voice on this score. Yet for mine, what has been done (the name changes) isn't right - your counter-intuitive thinking isn't without merit.
Cheers,
JR