The way I see it is customs is doing a random check. So if your parcel catches their eyes when going through the scanner then they will channel it to the red lane for further checking and the rest will go through the green lane for delivery. GST will only be imposed on those parcel that got detained in the red lane. So it depends on your luck. If you are lucky, your parcel will get through the green lane and you don't have to pay GST.