So you are suggesting that all sellers use couriers?

I can guarantee that sales will fall through the floor on ebay.

There are areas in Australia who have no delivery service except Australia Post.

Many buyers are not home during the day to accept courier deliveries and cannot make alternate arrangements.  They just will not buy if they know they will not get their items without major hassles.

While Australia Post is not always the best option, sometimes it is the ONLY option for buyers.

Many of us do not bother to track items every step of the way and we still get items in good time and with no problems.

If it were only courier delivery I would stop buying on ebay and look for another online option.