Even at cheap China Post shipping rates, there is a surcharge for tracking /Delivery Confirmation.
So some sellers shove in any old number, because most buyers don't bother to check it anyway.
And Delivery Confirmation only notes that the postal system has received the shipment and that it has been delivered, anyway. Nothing in between.
Keep in mind that tracking/Delivery Confirmation and tracking are Seller Protections, there to help a seller disprove a false claim of non-delivery. It provides no real benefit to the buyer.
If your item does not arrive by the last estimated date you have been given by eBay, you can open an Item Not Received dispute in the Resolution Centre below.
If the shipment arrives while you are away from your house, the lettercarrier will leave you a Notice telling you where and when you can pick it up, usually at the nearest Postal Outlet the next day.