This policy is also the same as the generally more lenient and accomodating Qantas. Their "Same day no mistakes" allows you to change the fare / destination without a change fee, but you have to pay fare difference.
I once begged-and-pleaded with them to allow refund on a flight which I could have booked cheaper a different way, but they wouldn't help.
You also could also be confusing this policy with the 24-hour cancellation policy for all flights originating the US. The US DOT requires all airlines provide a full refund of any fare booked within 24 hours, should the purchaser wish. This policy also applies to JQ and QF fares originating in the US (but not for travel to the US)