I buy things mail order from the UK semi-regularly. The usual method of complying with these regulations seems to be simple postal insurance (which is cheaper than a tracked parcel service that requires a signature on delivery).
If the parcel doesn't arrive, the seller lodges a claim with their insurer after a certain period has elapsed and sends a replacement shipment. It doesn't eliminate the chance of fraud, but it lets the seller transfer the liability at a fixed price. It also helps cover any monetary losses in the situation where a delivery has legitimately been lost.