From my own experience with Simple Delivery, if you use Royal Mail only, your buyer will be charged £2.27p for a small parcel up to 1kg and £3.03 for a parcel up to 2kg.
Most clothing items would be in one of these sizes. That is for RM Tracked 48. Buyers do not have to pay £7.
I haven't seen any reports of people scamming sellers with the new postage and I am not quite sure what you mean.
If the item is delivered, tracking shows delivery.
If the buyer opens an 'item not received' claim, the tracking will be checked.
If it is shown to have not been delivered, Ebay compensate the buyer and pass the payment for the item to the seller.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)