I can remember when I was a travel agent having to explain to people that L class is in fact a pretty low yield subclass - now you might say "Hang on a moment , an RTW fare is not cheap" but the problem is that by the time the airlines pro-rate out the various sectors the truth is that there is not a lot of revenue for them individually ( this is one reason why I always used to discourage pax from opendating sectors even when fare rules permitted it - better to be stuck with a confirmed seat that isnt quite your preference than to be stuck without a confirmed seat when your visa / money / schedule is running out )

Each airline has its own procedures for clearing ( or even for accepting ) waitlists and from what I remember QFs criteria are quite stringent - you did not explain exactly what you mean by 'recently' but please bear in mind that Dec/Jan are Summer school holidays in New Zealand and Australia and so there is quite a lot of competition for the lower yielding classes at this time of year ( even on a route like SYD-AKL with several daily frequencies ) I used to work for a major consolidator in New Zealand that had an 'inside' relationship with QF and I can tell you that in more often than not we had to advise pax not to waste their time waitlisting in L class as the request would either not be considered by yield management and so would sit there on waitlist forever without actually moving , or , would actually be rejected outright as not fitting the waitlist eligibility .