I think you will find that is not strictly true. The Royal Mail collect the due custom charges the same as business collect the VAT on a purchase. They do not pay for your parcel. I spent many years working for Royal Mail including about 5 working for Royal Mail international. I have worked with the customs guys from London, Dover, Birmingham and Glasgow. I have worked on international cross charging for the Universal Postal Union. My point was that I thought £8 was excessive. No different to, back in the day, when we all went into the post offices to buy our road tax. The counter staff would take your cash and the post office counters had at least a 30 day account to transfer that money on to the government. The interest on all of the road tax money held for those 30 days accounted for multi millions of pounds in interest for Royal Mail.