1) I wonder how they are going to discern between sellers who pack well for the p&p, and those that would not even if they knew how.
2) Will they take into account multiple item discounts which cannot be specified automatically because the sellers wares are all different shapes and sizes.
3) Will they discern between those who circumvent fees by selling a £10 item with p&p of say £2, for £2 with £10 p&p ?
And of course with the latter if the item is lost in the post (or deliberately not sent) the unlucky buyer will only get £2 back from the postal service instead of £10 and the seller keeps the surplus, a nice little racket seen only too often.
(Correction: I can't count (Two points !) and no one noticed or perhaps you were all being polite, that must be it
)