I can understand when it's something really big, like a container; the carrier gets slugged by customs to inspect it (even though it's their job and it should be paid for by tax?), then they get charged because it's taking up warehouse/wharf space until customs decide what they want to do with it... then maybe they get some kind of bill for the import duty etc, so they add it all up and pass it on to you.
I don't understand how they rack up so many costs with a package that can go straight through and x-ray machine and clearly has the contents and price on the front of it. You find yourself thinking 'sure that's why I paid extra for this courier/parcel service, so that all these fees (but not tax or duty) should be included.' - If when you bought it you were told, 'there is a £18 handling fee added to the shipping for entry into the UK' you may not like it, but at least you'd know before hand.
