I buy from all over Australia and when the seller notifies me on EBay that the item has been posted I tend to believe them but I have noticed that 2 or 3 items bought at the same time and stated as posted at the same time arrive days apart. Is the facility on EBay to notify of "items posted" based on a trust that they (the seller) are telling the truth?

I've even bought items from buyers in Queensland and Melbourne at the same time and the sellers have notified me that the items had been sent on the same day yet the Queensland item has turned up 2-3 days earlier than the Melbourne item both of which are using standard Australian post. I live on a farm Tasmania so it is a little confusing.