I don't think most people in Auckland or Christchurch or Napier have any idea there even is a Yellow Fever zone Andy, let alone what it is all about. I think the "everyone knows..." view is very much what it looks like from the inside looking out, but not from the outside looking in.
I think the only way to eliminate the problem is ( a ) making it VERY clear on the ticketing website i.e. with a pop up that only pops up once you've selected the Fever Zone that explicitly states "This section of the crowd is reserved for people who want to STAND UP for the duration of the game. Do not buy here if you want to sit down." and ( b ) Signage at the ground indicating that the bay is for standing and chanting, and ( c ) actually bloody briefing the security staff.