There is no such thing as Free Delivery, you say yourself Buyer Pays one way or another.
That has always been the case, either include in what they pay to you the seller, and you then use buyers money to pay for postage, or the new option where buys and sends through a label for seller to print.
However if ebay gets the postage wrong as seems to happen you can ot expect buyer to pay more.
In my opinion it is always best for seller to be in control of postal costs, and posting. As I would never use a Courier I have not noticed what ebay offers.