Given how simple this is, particular if paying through secured channels, it’s quite an extended conversation over nothing really. The seller is responsible for the delivery of the goods, and if the buyer paid through PayPal or another buyer secured method, if any loss or damage occurs during transit it’s the sellers responsibility, whatever they say before the sale and whoever arranges or pays for the courier.
If the buyer just made a bank transfer, PayPal gift etc then yes, entirely a gentle(wo)mans agreement before any money changes hands.