To answer the multiple "Why" questions, because I'm sick of companies making stuffups like this (most of which are NOT as obvious as a $1 ipad), and simply not caring or bothering to double check things on their public facing websites, because they know that if they do stuffup, there are no consequences for them.
The CGA is very good at ensuring consumers win over retailers in many ways, but lagging here. Either start forcing them to provide at the price advertised, or start whacking massive fines on them. If they got fined 10% of their annual gross profits every time they made these mistakes, they simply wouldn't make these mistakes.
There absolutely are consequences for them, and the only reason I can imagine someone is "sick of them" is if they keep trying to buy these obviously mispriced items and have to wait to get their money back, which should be an obvious risk you are prepared to take before you purchase the item. Other than that these instances are incredibly rare when you look at how often pricing is updated on NZ online stores, and you don't have to involve yourself with them at all when you can see its obviously a pricing error, generally all you're doing is creating more work for the retailer to undo and wasting your own time.