As doubleu says, it appears that the salary offered is based on NZ rates, if that's what the market dictates then so be it, if they don't get any suitable applicants I assume they'll have to increase the pay.
As with most agencies, they'll quote potential employees the bottom line because that gives them their maximum profit margin, and if you've got the balls to argue, they'll work it up from there.
Its not slave labour, and no one is forcing anyone to apply.