I also see this every time I check in for my Air NZ and Jetstar flights here in New Zealand. But I suspect like many I just by habit press 'No, I don't have any hazardous things to declare.' to move to the next stage of the check in process as quickly as possible! There are also signs and stickers on check in desks for those checking in manually -- but not sure how good the agents are at bringing people's attention to that.