neb: I've been to a number of ANZAC day services (see my previous post) and firstly they're not that massive an event, the biggest one in the centre of Auckland has maybe a few hundred people (not included the participants like bands, current servicemen, etc), and secondly the attendees are ex-military and military families, not random yobbos at a beach party. If they're told to stay home one would expect they'd follow the order.
I'm not quite sure what service in Auckland you go to but the main Auckland dawn parade normally gets up to around 20,000 people depending on the weather. Numbers in Wellington would be up to that depending on the year as well.